Fixes what Empire got wrong, but leaves out some of the things that made Empire great. If you are interested in multiplayer, I would rather recommend Empire as the game is more balanced. Napoleon suffers from balance issues online. Everyone tends to always either play England or France as they're the strongest nations, and there aren't a diversity of playing styles like there are in Empire. I also find players tend to play quite dishonorably by camping, spamming artillery, unicorns, or other cowardly tactics.
For campaign: I found Napoleon to be very fun, although slower and a bit more challenging than Empire. What I missed was the epic grandness that was in empire, however fighting in regions as opposed to countries made much more since. I didn't like how I could easily march a stack into Paris and completely take down France in ETW. The Campaign AI is also much more sensible, and you have more diplomatic options like Joining Wars, creating Trade Embargos, and Cancelling Alliances.
The battle AI is still terrible. A half-decent player will mow through battles to the point that fighting battles will get tiresome, but necesarry if you don't want to get screwed by the auto-resolve. I must admit after 3 hours, fighting armies gets downright annoying.
Still, it's an enjoyable game worth getting. However, Empire lasted much much longer in terms of replayability, grandness, and online fun. Napoleon's online experience is extremely disappointing.
Update: Still tons of bad players in this game. If there were a better community you might see me playing more often, but every game is hosted by a coward trying to tip the rules in their favor, camping in spawn/deployment with artillery, putting weather that disadvatages one army over another, just lame ♥♥♥♥. I've only had a handful of enjoyable online MP games in napoleon. It's still terribly unbalanced with a terribly poor community. So many ♥♥♥♥♥♥♥♥ players. Most of them have memorized the maps and how to exploit them, for instance, playing ottoman on desert maps with high dust and camping in the corner so enemy will be exhausted no matter what they do. Adding an extra 30 mins to the game just so they can win without using any tactics. If you like REAL battle tactics, this is NOT the game for you get EMPIRE instead. If you like doing cowardly ♥♥♥♥ and playing like a ♥♥♥♥♥, then get napoleon and just the rest of the ♥♥♥♥♥♥s with no skill.