I'd love to know what kind of accent Travolta thought he was speaking in, but mostly he suffered from something I know I've seen before, though I'm not sure where (possibly Wesley Snipes in To Wong Foo, Thanks For Everything, Julie Newmar): He doesn't play the character as a woman, or even as a drag queen. He plays the character as a straight man in drag, with a bit of a "wink" to let the audience know that "I'm just playing around here, you know - I'm not gay". As a result, he holds back just enough to make the whole performance seem uncomfortable and unconvincing.
Beyond illustrating the dangers of stunt casting, it was a competently-filmed version of a Broadway-musical-ized movie, but the original film was still better. For one thing, in the original film, the whole theme of racial integration sort of snuck in. It paradoxically gained power by not being the main focus. In the Broadway version, it's there pretty much from Scene One: The very first Corny Collins song talks about the "white kids" on his dance show. It's obvious right from the start that racial integration is what Hairspray is "about", in this incarnation. That may also be what the original was "about", in some sense, but it made its points with more subtlety. And there's a word I'll bet you never expected to apply to a John Waters film, eh?
And, another in a continuing series:
Things I Learned from Saw III