Cat isn’t terribly exciting and long-term isn’t terribly terrific either. There’re multiple reasons for this.
For starters, she’s meant to be played as a weirdly bulky offensive DPS. You know, Morph, 3-7K HP/regen for 3T. Unfortunately she is a Berserker, and one with only soft defense and not any hard defense (e.g. Protection from Arrows, Battle Continuation, Invuls), meaning she has no hard protection from enemy NPs and a sufficiently buffed up boss of any class can yeet her dead. Making matters worse, she’s (currently, that gets fixed this Anni) punished for using her NP. The hard defense also gets fixed, specifically this NY, by way of giving her an invul attached to her Curse (which is currently something that matches the ~lore~ with Tamamo (Caster) but does not at all mesh with her kit). To boot, right now her damage is rather mediocre, although support Caster Scathach-Skadi dropping this Anni will amp her up with Quick steroids and a 50 charger, a wonderful companion for her.
That all said, she’s still a bulky AOE Berserker and that’s not exactly a niche that’s very in-demand so-to-speak, because it’s always safer - if you care at all about the “most efficient play” or whatever the junk - to simply quickly delete enemies and she still has sub-par steroids and stiff competition as a bulky Zerker (Cu (Alter), Vlad in a sense in his optimal comps, Heracles), because she’s still going to get hit at x1.5 damage by everyone. That and, well, units like Herc and Culter are still outstanding at their jobs, able to handily and respectively clean up or solo in various hard content (e.g. Culter’s soloing various Gilfest CQs). She’s markedly better at what she does after no longer being punished for using her NP and getting some hard defense to stack up multiple sources of survival.
Making matters worse, as mentioned, her damage isn’t too hot due to minimal in-kit buffs. Offensively she’s outclassed by Fran for raw nuking at every possible level or point of comparison, and in terms of NP refunding/NPing multiple times post-Skadi (or even now for more fleshed out rosters), Zerkerlot is handily one of the best units and far superior to her with his NP Gen Up and powerful 3T crit amp and NP that hits a lot of times on top of not needing to work around a self-Stun. She’s just… not someone that excels in any particular niche, unless you include the one that kind of doesn’t matter at all.
That all said, if you like her or even love her, keep using her. Game, particularly the main story (especially as it is right now), is not that hard and is meant to tilt you towards playing with favorites. “Meta” and “efficiency” only matters if you at all care about it, otherwise it’s just a time-saving thing that exists and stuff. I’ve seen her used in CQs just fine, just gotta play to her strengths and minimize her weaknesses as anyone else after all.