I've been a fan of the musical version of Les Misérables since I first saw it on Broadway in the late 80's, so I've been excited about the movie version since I started casting it in my head that very same night. (Kevin Costner as Jean Valjean; Jennifer Grey as Fantine.)
And now seeing the movie 25 years later I understand why it took so long to get it made. It's something of a lose-lose proposition.
The rule of thumb in adapting material for the screen is to know that film is a different medium and therefore being slavishly faithful to the source material is almost always a mistake. But the problem with Les Misérables is that 60 million people have seen it on the stage, and my guess is a good percentage of those (like me) have committed most every word and note of it to memory. So "reinventing" it would likely turn off a lot of fans who are singing along in their heads. (For those who don't know, this show is 99% sung from start to finish with almost no spoken dialogue.)
The irony to me is that what made the musical work so well on the stage was how liberal they were with their source material. They took a 1500 page 19th Century French novel and edited, shaped, molded, reinvented every aspect of the story's broad strokes to create a totally modern (very British) stage spectacle, which blew me away. But when it comes to the movie, they just pretty much do what was in the 25-year-old play. And much of what works about the play also works on the screen--I was moved by the epic scope and universal themes. But even more of what works about the play falls flat in the movie.
For example, most of the indelible show-stopping moments from the play simply don't translate to the "real world" language of a mainstream movie. Examples: All the characters coming together on stage together on the first act closer "One Day More"; the students marching in lockstep looking like they're moving forward but they're not in "Do You Hear the People Sing"; Javert's suicide. I think they should have gone for it more and used all the tools unique to cinema in 2012, but instead they just filmed it in a very restrained, conservative style. I would have been curious to see e.g. Baz Luhrmann's do this.
Also a lot of the plot shortcuts that you can forgive on stage seem so much more glaring on screen (e.g. Marius and Cosette speaking for two minutes before committing to each other for life.)
I love Tom Hooper's choice of having all the actors sing on set to a live piano (later replaced by orchestra), but this too often goes overboard with actors starting and stopping as if to make sure that we're always aware that they, not a pre-recorded music track, are deciding the tempo. Also they seem to mix all of the music low, I guess so we understand the words?
All the cast are great and well chosen (with the exception of Russell Crowe whose performance is hampered by the fact that he cannot sing) but there are too many extreme closeups and too many tears streaming down faces. These songs are awesome - you don't have to cry through all of them for us to get emotional weight.
Also it is super weird that famous American actors (Anne Hathaway & Amanda Seyfried) sing in a British accent while pretending to be French. Perhaps they thought it would be even more distracting among the otherwise British/Australian cast for them to sing in their normal voice?
Anyway I'm glad I saw it. Movie musicals are really really hard to pull off. My favorites: Hair, Moulin Rouge, Tommy, Wizard of Oz, South Park.
PS: Extra points for casting Colm Wilkinson as the bishop. That was great.