In a way, reading all the negative reviews of Crowe's singing helped, because he was nowhere near as bad as one might have expected based on what some people were saying. I'd rate his contributions as ranging from adequate to good, depending on the song; he's no Philip Quast, but he serves well enough, and in a few places (the arrest of Fantine and "The Confrontation") I thought he was really standout; the latter number is really well-staged.
Jackman, Hathaway, Barks and Redmayne were all terrific. I thought Amanda Seyfried was good too, though Cosette is a pretty thankless role in a lot of ways (her reaction shots at the end are wrenching).
as a musical is a challenge to film in some ways, because it's full of long, angsty solos that aren't especially cinematic. Hooper eschews what I suspect would have been most directors' instincts, to incorporate montage elements into them, in favour of continuous extreme close-up, which has proven controversial, but I think really works (in a way it seems like can't win, either he's being called too conventional or too unconventional).