She seems to be a bit popular in the competitive 5v5 games, but unpopular and kinda bad (at least according to the win rate) in solo games.
I've been testing her a bit and my guess would be, that it's because she is extremely squishy and she can only deal damage in 2 ways:
2. WE/EW combo
The 2. is very unreliable without other people's cc and 1. is obviously not enough to kill someone. She is bad in teamfights and easy to focus down, since she has to get rather close in order to hit E or W.
Her early-mid game is decent though, mostly due to the spammable high damage Q and ganking ult.