I'm not an expert, but from what I've seen she suffers from some problems built into her design. Izayoi isn't really able to do anything until she gets stocks, and until then she's rather underwhelming. She can do some really cool stuff once she gets resources, but until then she has to give up a lot of momentum to get stocks (most of her combos in normal mode put the opponent into the air and resets the game to neutral instead of giving her oki).
Compared to say, Hakumen, another character who relies on gaining resources for better moves, but haku's resources just fill up on it's own, whereas Izayoi has struggle for hers. Most other characters don't rely as heavily on gaining resources either.
Also she has poor defense even though her offense isn't that scary and her normals are a little weird I guess.
And of course best to take this with a grain of salt since I haven't been able to play CP yet