I think maybe the film's status as a musical is part of the problem here. Les Misérables is a big novel so any adaptation of it has a lot to cover. This is a long film, so that should not be a problem, except that with so much of the time devoted to introspective songs the narrative has to be truncated. This can be the fundamental problem with musicals - the viewer often ends up thinking "shut up with the singing and get on with the story". I understand that in the relatively recent past the creators of musicals came up with the idea of taking parts of the narrative and turning it into songs, instead of having the songs as a break in the story. This is not really an approach used by the creators of this film of Les Misérables.
I also felt that that the songs in this film were not that great, which is a bit of a problem for a musical. That, obviously, is a controversial comment when said of a film adaptation of one of the most successful stage musicals ever, but I found the songs to be mostly flat and unmemorable. There were some exceptions to this, like the 'I dreamed a dream' song or the revolutionary anthem, but most of the rest seemed whiny and inconsequential.
The politics was maybe a bit thin too. The revolutionaries seemed like a bunch of fops with no programme beyond "Liberty!" and the like. At one point it looked like you were meant to think they were naïve idiots, but there was a shift in their tonal representation after they stage their revolt and are crushed. At the end of the film it is even suggested that heaven is one giant barricade full of people singing revolutionary songs - a truly terrifying prospect.
Poster
barricade