Loved Quinn from the moment I saw her and I play her on and off, not for any negative reason but because I like to play all roles. Anyway, to me she's one of those few standalone champs. If your support is being an ass-hat and not playing correctly or DC'ed, you can trust on Quinn to play well on her own, which is why she is so good by herself in the top lane. Her survivability is high thanks to her E, Vault, and her R, when she transforms into Valor and gains massive Movement Speed.
Her passive is rather strange in that it goes off whenever it pleases and can make last hitting champs and minions troublesome but with her E your passive is immediately activated on the champ you clicked so that's always nice. Her Q gives her the upper hand before minor-skirmishes so that she can blind her opponent(s) and mitigate some damage. Her W helps her detect possible ganks and her E allows to get out of a lot of sticky situations like Jarvan's ult and she can also use it to scale walls if positioned correctly. Her E doesn't give a rat's ass if your opponent blinks or dashes away because she will still follow through, but this could cause you to land around enemies so be careful.
Her R is a double edged-sword. It's magic in that it potentially allows her to take down turrets and whatnot fast thanks to the increased Attack Speed and it also allows her to escape thanks to the increased Movement Speed. On the other hand, she does turn into a Melee champ and she loses all her range and that puts a lot of people off.
Ultimately, she's really fun to play and can be a bit tough to understand in terms of skills but if you just practice a bit with bots and get to know her then you'll be fine.