Passively, she's Mk23 with better tiles. Regarding her active abilities, she isn't as nice as Mk23's straight damage upgrade for some, but better for others (such as fights with Grape that require her to shoot faster). They're similar but not interchangeable so you'll need to use the space between your ears.

Also she's kind of boring and has no easy jokes besides the Viking name, which doesn't suit her at all, so blah.

Babushka says not one step backward. Every seventh shot, she gives a damage bonus! Also, the thing starts active, making her one of very few buffers with a start-of-battle skill activation. Her first skill is still defensive in nature, and the percentages got bigger. She's actually useful in a number of situations, either for reducing enemy firepower in specific fights (usually Gundam or tank related) or just the straight DPS boost from the get-go. You only really need her up to Mod 2, but the Mod 3 art is cute.

Her pre mod form is here

"Yay, we can all clear singularity now!" Oh wait... :V Fucking Ceia, I swear...

Yeah, she's a little over-hyped, but she's actually a fairly solid unit. A stacking buff every few seconds? Not bad at all. This allows her to buff firepower, accuracy and rate of fire all at once. Her main issue is it takes a few seconds for her skills to REALLY kick in, but she's great for the longer fights that start creeping up here and there, and for things like backing up M4 in her railgun mode. Not super necessary compared to before now that we have lots of buffing HGs, but she's handy for things like ranking maps.

Another fun thing about this mod you might not know is that the passive 2nd skill automatically activates on a cooldown that you can't see, so rifle tile buffs (which speed up handgun cooldowns) make this activate faster.

Her Mod 3 equipment is kinda pointless for her role, though, so unless you like the art or have bad OCD, she's fine at Mod 2.