I agree with Moms4lif3 She is a solid character... but has some really bad MUs. Hellboy's Air Grab can be used on reaction to completely nullify her jump in. Check out Revet vs Dab on #WarofTheGods for an example. I do not think there is anyway you can turn up to an event and expect to get to Grand Finals.. she needs some support from a pocket char for those bad MUs. Granted even Catwoman can be totally shut down by Captain Cold but Cheetah has more MU problems than a single char.
What makes Cheetah a target for noob rage is her damage output. On paper a char getting 800 dmg or w/e "sounds" broken.. but when you look at how she plays and what it takes to play like she dose .. it is not nearly as "broken" and nubs think.
To get her damage she needs to spend trait as well as 2 bars minimum on meter. Those big massive famous damage totals are 3 sometimes even 4 bar combos. This is how she is designed at NRS.. she has an unusual meter usage. She is all about taking damage, playing defense, opening you up and then dumping everything for massive burst. It is actually really hard to play, and you often are a health bar behind at times before you get your chance to do anything. She excels in forcing early breaks.. as once they have broken you can save your meter and dump everything with no fear of the breaker.. only air escapes.. which unlike many of the cast are a real problem for her combos.
Compare her to Catwoman and Supergirl or Hellboy and more.. who can not reach the same damage totals but can get 400ish meterless with no trait... If you really look at it that way no one can seriously claim she is broken, she is in NO WAY worse than most of the cast.. she just plays differently and that playstyle results in spectacular burst damage, which trigger people.
Cheetah is a great example of what I consider noob attitudes to fighting games. "on paper states" mean shit. Just as she has high damage output which on paper looks OP.. means nothing as you need to take in everything else not only about how she plays. but how everyone else dose.
All in all I would rate her balanced. She is an great character but they have built in a number of issues into her design as well, which makes her not even close to the top of the pyrimid tier list for injustice.