[quote name='bburpee']Why surprising? The cast looked like the strength of the movie. The dancing looked lame.[/QUOTE]
It was surprising because Jennifer Lawrence is still a relative up and comer, Bradley Cooper doesn't have much in the way of serious acting experience, and Robert DeNiro is coming off of a long string of laughably bad roles (remember that terrible cop movie he was in with Al Pacino, Righteous Kill, I think it was?). Hell, even Chris Tucker did great in a role as a character whose premise borders on slapstick.
Also, the dancing stuff was really, really low key. They aren't heavy handed with it at all. You could almost argue there's more relation to jogging in the movie than dancing.