The movie has many high points. I'm sure you've heard by now the revolutionary approach Hooper has taken in having the actors sing live rather than pre-recording and having them lip-sync during the filming. This is probably one of the stronger aspects of the movie. You can hear and feel the raw emotion (in a rather emotion-drenched movie) from the character's. Their actions, their sobs, the way they enunciate or punctuate their songs has never felt more real in a movie.
Other incredible characters are Eddie Redmayne (whose singing of "Empty Chairs" is close to flawless, even making me forgive his quivering chin that vibrates as much as his voice), the little Isabelle Allen in a tearjerker performance of little Cosette, Samantha Barks in an impressive performance of a role and song that everyone knows. It's even more impressive knowing that she isn't a big-name actress, but more known for her theatrical roles...which makes me wonder why Hooper didn't take that approach with some of the other characters.
This question came up the most for me in terms of Russell Crowe as Inspector Javert. When I first heard he got the role, my first reaction was "Can he sing?" and: "Why?" Crowe can indeed sing, but not comfortably enough for my taste. There are times when I can almost see the uncertainty and panic in his eyes. And although he serves as a good placeholder for Javert, the word "placeholder" is not what I want to think when it comes to Javert. I want an antagonist to despise, fear, and to relate with at the same time. Crowe's Javert doesn't give any nuance to a role that is tailor-made for drama and love/hate villainry. Furthermore, out of everyone, he looked the most out of place in his costumes.
The movie does its best at stirring the blood and raising the arm hairs when it needs to. It does tend to plod along however, and since it's a musical more suited to intermissions, it feels longer than usual. And as paradoxical as it seems, seeing it in movie rather than on stage makes it feel smaller, for some odd reason. Hooper adds majesty through the use of force in the musical -- the sheer mass of people in a shot, for instance -- but the movie lacks a grand punch in other aspects. It appears to lack a cohesive element and makes the third act seem like a hodge-podge of side quests and plots rather than winding the thread of Valjean's redemption together.