For starters, all previous dual-operative releases have had one dps and one support, and the duo have always been designed to work together, so we won't know for sure how well Mia works until we can actually test how well Haru - Raikou works, but in a way it also doesn't really matter, as Mia needs to work well on her own even without Haru, as well as work well with the other operatives we already have.
For example Starchaser needs to work solo for Co-Op play where Haru might not be around, or for new players down the line who get Starchaser but don't yet have Raikou.
Nerida - Styx Envoy was the mistake Seasun made when they made one operative so incredibly perfectly matched with another operative (in that case Marian - Riptide) that you wouldn't want to use one of them (Nerida, in that case) unless you could use the pair, and I have no doubt they won't be making the same mistake again, with the previous supports like Phantasia or Freefin working well in their own right, and the main dps operative like Rhapsody and Phantasia also still working well without their main support partner.
Thinking about it, Nerida also has an outfit also had several functionally useless or outright unusable zippers on it just like Mia's store outfit does... hmmm. Hmmmmmm....
The TL:DR: is that Mia is a strong operative and is probably the perfect operative for casual play, but she isn't perfect and does have a few caveats.
In a nutshell, Mia is the combination of 5 parts Bubu - The Geomancer, 3 parts jiggle physics, 1 part FuwaMoco, and 1 part machine gun.
Whether that mental image is an unholy abomination or unfathomably based is left up to the reader to decide...
(Apologies to the Ruffians for that mental image regardless though...)
The Window Licker
Yes, I am going to call her that, both because I think it's funny, but also because it's far more appropriate than anything else I might want to call her...
The first meta commentary I did on this site was for Clarina in v3.1, in which I started by explaining how Snowbreak had mostly had skill-damage operatives for a long time at that point, but all the recent supports were ballistic, and how Bubu was notable for being the exception to that cycle.
I also pointed out how well-liked Bubu was, both because she was adorkable and fun, but also because she was a purely ballistic dps operative, which we hadn't had in a long time.
Clarina herself was a tease who didn't technically shoot anything, but now we have out very own window licker, Mia! ... and Mia actually shoots stuff!
My comments about Bubu are more than just preface and window dressing this time around though, as Mia plays almost the same as Bubu does.
On the one hand, this does mean that Mia has a lot of the same strengths that Bubu has, but whilst Mia has fixed many of the issues Bubu had, some problems do still rear their heads, and some of them are annoyingly familiar...
How does Mia work?
Mia's ult works similarly to Bubu's, whereby shooting stuff charges her ult, which you can use to more quickly fire shots that deal increased damage.
Mia's ult only stacks to 2 charges, which is enough for 8 shots, but otherwise the mechanic is the same.
Mia also has the same mechanic Bubu has whereby she can't move whilst shooting, and can only do a short hop in-between bursts, except with Mia that now applies to her standard shots as well as those from her ult, so Mia has even less manoeuvrability than Bubu does, and makes Mia one of the least manoeuvrable operatives so far.
This also has the knock-on effect that Mia can have pretty terrible survivability, as she can generally either deal damage or move, but not both at the same time.
Her standard shots work similarly to Bubu's, whereby you fire a quick burst of shots and automatically reload.
Whilst Bubu fired in a 1-1-3 pattern and reloaded after the 3, Mia fires in bursts of 2 and reloads when her mag is empty, which is a more fun and consistent way of doing it, although Mia kneels every other burst, which throws her aim off a little, meaning that Mia's long-range dps can be shockingly poor as most of her shots will probably miss unless you slow down your rate of fire massively to correct your aim for every single burst you fire.
Where Mia differs the most is that Bubu's standard skill charged up her standard shots for more damage and bouncing between enemies, Mia's standard skill instead charges up a huge cone AoE. This gives the window licker the best AoE damage coverage of any operative in the game, which will probably make her very popular for casual play.
Beyond that Mia mostly works how you expect - she has her own logistics squad that works with her and nobody else, she has a signature weapon that works with her and nobody else, her Manifestations do roughly what we'd except them to, and she has a new outfit in the shop.
The most notable thing about Mia is that she gains quite a lot of buffs from reloading.
This means that she wants to ideally reload before entering combat, so her first shots are already buffed, instead of firing unbuffed shots until she reloads and gains the buffs.
In her Operative Trial stage, Mia starts out dealing around 25k damage per shot, which quickly goes up to 32k, then 42k after she actually reloads.
Going from 32k to 42k just by reloading is over a 30% increase - that's a huge amount of damage to be missing from your opening salvo.
Since her buffs are quite short lived, this comes up with boss invuln phases as well, with Mia suffering in any boss that has an invuln phase - Mia must either pre-emptively reload to maintain her buffs, or she must let her reload buffs expire and then shoot until she automatically reloads and regains the buffs.
This is an annoying design, and it affects both her 5* weapon, her 4* weapon, and her logistics set.
Thankfully her standard skill does technically give a reload when used, so against groups she can maintain her buffs.
Also of note is that my testing shows that Mia does not benefit from effects that grant her extra Shotgun pellets.
This is annoying because Mia is an Electric operative who uses a shotgun, and there are only two 5* Electric Shotguns in the game - her own signature one (Skirted Confession) and Sunny Payback, and Sunny Payback gives an extra shotgun pellet as part of its unique effect, which Mia can't benefit from.
Sunny Payback is still a good weapon simply due to its sheer ATK stat and slightly better reload time, but not being able to make use of its effect means it doesn't really outperform her 4* weapon, and that Mia can't use its effect is really annoying and just adds to the feeling that she wasn't quite ready for prime time yet.
Her standard skills AoE atack does feel somewhat tacked on too.
Much like Fenny - Pureheart last patch, whose RMB attack didn't quite work properly with the rest of her kit due to things like it not charging her ult, Mia's standard skill also doesn't feel like it fits into her kit well - the technical reload (which isn't mentioned in the skill description, but you can see via experimentation that it does proc her reload buff) feels tacked on - a fix tacked on to her standard skill to fix to a problem the skill itself caused by not working with her logistics and weapon buffs.
Her standard skill also can't crit - despite all of her other damage being guaranteed to crit, but it's all ballistic damage, which feels odd.
Her standard skill also doesn't charge her ult at all, meaning that like Pureheart before her, her single-target DPS suffers if you use it.
Was it the case that Mia was worked on by two separate teams who had poor communication, was her standard skill just hastily tacked onto her existing design as an attempt to give her some AoE capabilities (much like I speculated Pureheart's RMB attack was...), or was it just the case that her weapon and logistic buffs were designed around an early version of Mia who got upgraded later on and the buffs were left by the wayside?
I don't know, but what I do know is that Mia feels somewhat incomplete and can feel clunky because of it.
In Bubu's page I point out how Bubu has some weird quirks related to ADS, as Bubu has an S-Energy indicated coin that can be difficult to see when in ADS depending on what Bubu is wearing and which direction she is travelling in (yes, really).
Mia has no S-Energy issues, but she also can't ADS - like, at all.
I think the trade-off works for her, but I feel that Mia didn't need to sacrifice her ability to ADS - she would work just fine with it.
Damage
Mia gains a huge weapon compatibility boost, as well as a massive boost to her base crit damage value, both of which means her damage per shot is very high.
Her shotgun does only deal 1 hit per shot though instead of the 8 pellets per shot that shotguns in Snowbreak usually deal.
Combined with her RoF being higher than that of a normal shotgun, Mia manages to deal respectable damage.
Mia isn't nearly as strong as the games current top-dps: Chenxing - Jade Arc, but that's a good thing - we don't need more powercreep.
Mia has quite mediocre single-target dps, but her standard skill allows her to deal good dps to a lot of enemies over a huge area, and against large groups she's fantastic.
It's possible that Haru - Raikou does supercharge her dps, but I seriously doubt Raikou will be that good.
Personally, Mia feels like she's in a good place in terms of balance - her damage is decent, her AoE is fantastic, but her mobility is poor, and she works quite well with several existing support operatives, all without breaking the game due to powercreep - she feels delightfully normal. Balanced, even.
Teammates
Mia's M5 gives her more damage if she has another Electric-damage operative on the team.
This is going to make the buff extremely unreliable in Co-Op content.
For single-player content, you can get Chenxing - The Observer very early in the game, who is a decent healer, so having somebody to proc the buff isn't an issue, but the better question is whom?
The Observer is fine, but she's not a ballistic support, so who is Mia's ideal teammate?
Even ignoring her M5, who works well with Mia?
Well, Mia wants ballistic, electric, crit dmg, and ATK buffs, and to debuff enemy resistances and DEF.
Her very high crit damage values mean that buffing her own crits can add a lot of damage for her.
This mean that her best supports are currently Yao - Nightglow and Vidya - Celestial Swan.
Yao provides ATK, ballistic damage, and crit damage buffs, which are exactly what Mia wants, and Celestial Swan provides the usual massive resistance and DEF debuffs.
Whilst this is fine, this means that what Mia wants are exactly the same thing that Chenxing - Jade Arc also wants, but since Mia deals less damage than Jade Arc, why would you ever use Mia?
Because she's fun, because she's cute, because you like her as a character, because she has better AoE at better range, sure, but if you want maximum single-target dps, and/or you want electric [ballistic] dps, Jade Arc will beat Mia every time.
It's an odd position for Mia to be in. Fitting for her character of course, she's the newest (and thus weakest) Heimdall operative, and being outclassed by more experienced members should be par for the course, but in terms of gameplay it's unsatisfying for the new operative to basically be a worse version of one we already have, at least for endgame content where single-target dps actually matters.
Mia thus deals essentially the same type of damage as Jade Arc, but less of it, and she plays about the same as Bubu did.
It doesn't feel like Mia puts anything new on the table (besides some saliva, of course), but that's fine.
Not every operative needs to change, rewrite, or completely break the game - Mia takes some elements we've seen in several previous operatives and combines them into a new package that is fun and looks good, and she has her own strengths and is the ideal operative in some scenarios.
The requirement for any new character in a gacha game is that they look good, they're fun to play, they're not useless, and they don't break the game.
Mia does all of those things, so I think Mia is a fantastic new operative.
Good job, window licker!
Welcome to Heimdall!