While he's not my favorite character, I will give in to fact that most of the most amazing and iconic quotes from the show are his.
In my opinion, though, he got worse after Season 4, not the movie. It just went downhill from there for Patrick.
I think the redeeming episode for Patrick was Patrick! The Game. Although he wasn't as funny as he used to be as in season 1-3, he still had some nice episodes here and there.