I just saw Burlesque this weekend, and I felt pretty much the same way. The music, costumes and dancing were great, but the writing and acting was just awful. It was like a bad TV show- every line so cliche. I don't know if they were trying to make it campy or what. If so, they should have marketed it that way - instead they tried to market it like a Moulin Rouge or Chicago, but it was not nearly as classy or well-acted as those films.
But I did enjoy the production numbers, especially some of the more classic Burlesque-style stuff.