Where are the explosions?
How do they expect to make any money?
Les Miserables is a great book.
It's also a great musical, although really quite different in parts of the story and where the emphasis lies.
It's a very long book, and a very long musical (relatively speaking)
Also, an awful lot depends on the two leads. Both the actors for Valjean and Javert must be able to sing, and able to act, and look the part. Jackman can certainly cover the first and the third; Crowe the third (and, when he's on form, the second). But can they hit all three?
And I'm also a little concerned about the high billing given to Anne Hathaway. Fantine is an absolutely key character... for about a third of the running time.
(Strictly speaking, she's also too old to play Fantine, but that's a nitpick.)
I cannot read it in the original French, but in general, it suffers greatly from being produced (as many such stories of the day) as a serial, paid by the word. There are many, many, many words.
The full musical typically runs 2 hours, 50 minutes, and that's including the intermission.
By comparison, LotR: Fellowship has a runtime of 178 minutes - just about 3 hours. So, a long movie can be done and still be successful.
Which makes her a fine highlight for early teasers - her portions are apt to be complete early, and they can pick and choose good cuts. That's important, as IMDB lists the movie as still filming. If they're releasing in December, post-production is gong to be short. Plus, let us face it, that song is iconic and good for trailers.
Is she? The actress is only like 30. I read the book a long, long time ago - I don't recall her the character's age being given expressly. And we have 20 and 30 year olds playing high-school students in highly successful TV shows...
Just a word about physical prowess- I bet none of the performers in the role in the musical were exactly buff.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.