I've been playing her almost exclusively (you can check my profile page to see how well I do with her), but I don't think S3 really changed her gameplay much.
Her Q still makes her an all-in champ because you can only target enemies with it. The CD is insane. She's very prone to CC and it's kinda dumb to build her bruiser-like. She's basically a walking ulti and will die very easily without it. But if the enemy team lets you snowball a little, she can pretty much shut down most ranged carries and dish out a lot of damage in teamfights.
I've been using her top, mid, jungle, and even as a bottom AD, and I really enjoy her versatility. That being said, there's better champs. Her Q needs work and her passive is amongst the worst.
EDIT:
Part of her charm is her innate weakness when compared to most of today's top lanes. She makes it fun to succeed. Plus, nobody knows how to fight a Fiora since nobody ever plays her. The highest kill score I got with her to date since S3 is 36-6, and I adore her.