Since Worf was wasted in Nemesis I just wish they had stuck him in Klingon clothes and called him ambassador. Putting him back in a uniform was annoying without giving a reason why. Granted it's all about appealing to new or casual viewers but I think they have to give something to the fans too.
I liked the idea of Worf as ambassador, and Worf as first officer (hello, Titan anyone?) or having a command of his own a lot more than what they did to him in Nemesis.