Phenomenal in that it kept you interested through the entire book. Some parts (particularly the political/historical philosophic digressions) were repetitive and harder to get through, but no more than you'd expect in a book this long. Tolstoy's ironic wit in the narrative was delightful. 
 The Russian to French names, and constant nicknames/alternate names for characters was confusing at first. 
 People just don't write this way anymore :) One of the greats for good reason. 
 On a funny side note-the action takes place just before that in The Count of Monte Cristo, which in turn is followed by the action in Les Miserables. And there we have three of the longest novels in the world.