An excellent cast makes this movie work; all of the characters are developed exceedingly well and it's clear that the actors enjoyed filming this movie.
It's not quite the comedy I expected, much more a lighthearted look at the attempt to reclaim youthful glory than bawdy humor. For music fans there are quite a few subtle references that in themselves are intelligently funny.
I hate drawing direct comparisons to other movies, but so much of this movie reminded me of Alan Parker films I can't help it: imagine if The Commitments actually did make it big -- and then tried to recapture said glory 25 years later.