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.
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.