I'd say go see it! It was a lot of fun and had very enjoyable music. They cut out some of the plot development in the musical and put in a few others to patch it back up, but I think the film makes sense on its own. The theater (Loews Boston Common) had some audio issues, and some of the lyrics were hard to pick out, particularly in songs with loud guitar. There was also some weirdness with lip-syncing, and the transitions from talking to singing weren't kind of awkward. But otherwise I think they really did take advantage of the film as a medium, putting in close-up and moving shots and inserting flashbacks and random footage during songs that were more plot development than action.

I have seen the musical before, but unlike my cohorts who know the soundtrack inside-and-out, I don't have the entire musical memorized, so I wasn't too distracted by the differences. :-)