Be under no illusion - this is seriously hard work. It's lengthy, and long winded. Several of the books that make up Les Miserables are pontificating and go on for quite a while. You will read for hours and very little will have happened, then all of a sudden, in the space of a few pages (perhaps a chapter) you find out almost the entire back story of certain characters. Then back to moments of nothing.
My only advice is to bite the bullet and get stuck in. Initially hard going, but if you persist, you will be rewarded. I'm a quick reader, and after 6 staright hours, seeing I was only 12% through I almost gave up. I honestly couldn't work out how someone had managed to pick out the story for the stage production I loved so much - I'd been reading for ages and nothing had happened! Yet all of a sudden, when Fantine is taken in by the Mayor, you won't be able to put this book down. I fell in love, I suddenly cared about the characters I thought I knew yet had not yet warmed to, and I wanted to know more.
Prepare for a book in the same vein and scale as War and Peace, get yourself into the mindset for a long journey, and you will love this book as I do now. It's a classic, and I strongly recommend you give it a shot.