I've only seen a few clips but the filmmakers clearly made some bad choices that make me sure that making the movie longer wouldn't fix it. They felt the need to replace Napoleon's bravado when returning to France at the beginning of the 100 Days with pathetic whining. In a clip I saw, Napoleon whinges that he misses his home and acts sad. In real life, Napoleon just walked in front of the troops with their guns ready to fire at him and said, “If there is any man among you who would kill his emperor, here I stand!” In response, the troops shouted, "Long live the emperor!" and joined Napoleon.
I don't blame Scott, I blame us for expecting more than this. How can you really do this story justice in one sitting? You can't. Better off just watching Waterloo if you're into the historical accuracy, military thing. It's absolutely amazing.