I read a version of Les Miserables that was only very slightly abridged by the translator. I really enjoyed it and think that it's definitely worth reading.
There are, however, a number of long digressions discussing Waterloo, convent life, and argot. These can all be skipped (if you find them boring) without affecting the story, except for the last chapter of the Waterloo digression (a few pages), which contains an important event for the plot.