I don't know enough about the actual history of Napoleon to say how much of this movie was factual.
However, I still don't know anything about Napoleon other than he crowned himself Emperor of France and was married twice. You would figure that having watched a movie about the guy, I would have a better understanding about him, but really it's still really only what I learned in history over 20 years ago in high school.
There are battle scenes that are incredibly gory. Does the dog die? Everyone practically dies. If there was a dog, it would have a bullet in it's head that Napoleon would have dug out. Sure it was impressive to see, but why were we shown those scenes?
But even the battles lacked substance. Why were you bombing the pyramids? Was Napoleon leader then? Or just the general of the army following orders? I don't know. Did that become part of the empire?
This was a highlights reel of Napoleon's life after the revolution. You're expected to know the characters, the plot, and the story. You aren't told any of it.
Napoleon himself in this movie seemed timid and scared. He was in the right place at the right time, and just sort of feel into being the leader. He didn't really show any strength until near the end and even then it wasn't as the leader of the empire, but the general of the army. There is no real connection between him and Josephine until letters written after their divorce.
If you are looking for a movie where you are constantly confused about what's going on, or you are a huge Napoleon fan and want to see some of his battles on screen, then I can say you might enjoy this movie. However, for everyone else... it's probably not for you. Also, if you don't like animals dying on screen, avoid this one completely.