Warwick is balanced, but that will be called into question once his ult gains suppression (meaning you can't cleanse right out of it). Warwick's niche is that he jungles very well and he can hold control of the jungle. He's a solid pick if your team has a champion that can 2v1 a lane w/o constantly dying or becoming underfarmed. Warwick's job is to make sure he stays at or ahead of the sidelanes while coming in to gank when the other team has pushed too far into his allies' territory.
Warwick's job later on, past the laning stage though, is sort of like Shaco's I think. He semi-jungles while hunting down people for 1v1 (or to catch low health runners and put them in the dirt).
Once his ult can't be cleansed, I think he will be a lot better champ then he is now, because Warwick depends on items.
Warwick, isn't BAD by any means, nor is he OVERPOWERED. He's fine and he's great at letting his team get ahead in levels and gold by taking the jungle while as the same time ganking the sidelines. Warwick varies from person to person, so if you think he's overpowered, its probably because you faced someone who knew when to gank and when to retreat and you just need to learn when to gtfo when you see the Wolf Eyes pop over your head.