A pretty good summary of the critics' views can be found in the article from the independent online.
It is suggested that the homo-erotic elements of the musical play a part, which I think is probably unfair. Firstly, there is no reason why art should not challenge conservative thinking. Mainly, however, it is because any homo-eroticism is actually more in the mind of the observer (and perhaps the director) - Anne Rice's vampires had no sex drive.
The main reason that this should have died before it started is that it was always going to be atypically a musical. Anne Rice's novels are of a darkly gothic edge. Musically both films based on the books - whether you appreciate both, one or neither of them - managed to get the music pretty much right, both in very different ways.
Elton John has done the music for Lestat (cue images of a vampire getting out of a coffin and singing "I'm still standing"). This is the sort of subject matter for which dark rock music was made, not bland formula pop. It might not have drawn a typical Broadway crowd, but it might have achieved critical acclaim and gained a cult following. If you think the music can't be that bad, nip over to the official site and check the trailer, there is just enough music to show I'm right but not enough to melt your brain.
Okay, rant over!