So far I've played almost every character in LoL right now. I like how they are all useful and, if played right, can handle almost anything. The downside is that you have to play most of them that one right way.
I wouldn't call this a bad thing or a problem, but I played Twisted Fate a bit ago and found that he's awesome when you stack ability power or if you go for attack stats. The different play styles gave him so much more appeal to me since I could choose him and then build him according to the enemies I fought were playing.
Basically, I love that some heroes can do that and I hope Riot gives us more heroes with that versatility.