I am by no means a high level player. I probably only play a max of ten games per week, and have never even tried ranked, so take this for what it's worth.
I've won 6 of my last 8 games as Zed. I'll play him top, mid or jungle, I don't care. I'm really just having fun learning how he performs against different champions, and just trying to figure out how to optimally use his kit. I feel like I've barely scratched the surface with his kit possibilities, since I know for a fact that I very rarely optimally use the shadow teleports on his W and R. Even still, I definitely have a winning record with him.
I understand why people say he needs a buff - his kit does seem underwhelming. But I really think it only SEEMS that way, because hardly anyone has really understood how to optimally use the teleportation mechanics in his kit (including me).
I'm only playing him because I really like his style, and I'm hopeful I can eventually master all of his mechanics, and unlock what I think will be OP. I just had my best game with him yet last night, when I went 15/4/9, with 354 CS, while Jungling. Not too shabby. 