I've been a werewolf for most of the game. There are no disadvantages to it and you can completely ignore it if you want, I just want to cure it because I'd like to try out being a vampire for a while.

http://www.uesp.net/wiki/Skyrim:Werewolves

Major spoilers!! I guess...

Please do not post spoilers in the general forum, that is extremely inconsiderate.
Normally if you sleep in a bed you get an increase to skill progression for several hours afterward, werewolves don't get this.

You can cure this (you are shown how to do this during the Companions questline), although once cured you can't become a werewolf again, and you can't do the quests associated with it (at least not Aela's, I'm not sure about Farkas and Viklas).

Thanks. Had already completed the Companions but didn't know I could perform the ritual on myself.

Is this not the spoilers forum?

Also, I can think of one other quest which has a very negative effect on you if you are a werewolf already.