It's really hard to say. I feel like (as far as ADC go) right now they all suck except for Vayne and Jinx. The two matches I've played with her I've gotten camped out hard both times and despite that still bullied the enemy lane really hard. She CSes very easily, she wins out trades very easily (the second match was against a caitlyn where I didn't think trades would be in my favor, but as long as I manipulated the wave I won them out pretty hard) and her dmg scales really well. The only real issue I have with her is a lack of a real gap opener, but with her trap thing if you itemize properly you have enough to get by.
Skill cap wise I don't think she's too hard. It's literally just get three stacks of minigun, switch to rocket, switch to minigun (rinse and repeat), landing your Zap! (which is kind of slow so you need to be able to read opponents), and internalizing the setup time on her trap. Her ult is the same as Ashe pretty much; you can try to snipe with it which ends up being a hefty mix of luck and skill, or you can save it for safer situations. Her ult is a lot less critical than an ashe arrow though. I think the hardest part is just having good positioning, with no real gap opener if you misstep you die. Same can be said of most ADCs though.