Napoleon Total war is probably best compared to Rome Total War: Alexander, in that it is built on an existing game, but is not quite an expansion nor is it quite a sequel. Also, Napoleon, like Alexander, focuses on one commander and portrays historical battles where you take the side of the famous leader (Napoleon in this case). The two titles depart there, though.
Alexander, in my opinion, was a flop. One main campaign that wasn’t that well put together and relied entirely on mercenaries instead of the fun country building of the other Total War games? It wasn’t worth it in my opinion. Napoleon, however, has several campaigns, relies significantly on nation building, as well as army management and battles. Either the developers learned from Alexander, or they decided to just take the game in a little bit of a different direction, either way it is a major win.
Naval battles are back from Empire TW, and they are much improved. The AI is better, the ships move and attack better (though manual control still is preferred most of the time for me at least), and you can repair your ships provided they are not being attacked. I can’t count the number of times I lost a ship because of sinking due to combat damage while it was out of the battle entirely. An added bonus is, so far I haven’t had a catastrophic crash to desktop from naval battles (which happened a lot and still happens randomly in Empire).
Napoleon also brings his artillery prowess to the field. Maybe I am imagining it, but artillery seems to act smarter and work better than it did in Empire. I’m not talking unit effectiveness, merely that it responds to commands better. It will sometimes kill your own units if they are too close to the target or there is a misfire, this is especially true with short ranged grape shot. I will say that grapeshot is much more useful in this game than in Empire, mostly because it seems to have been given a range buff. Artillery also turns more intelligently and the gun crews will defend themselves with some intelligence. I’ve always either lost a crew or intercepted attacks before they got to the artillery, but in Napoleon gun crews that are saved or that regroup can pick up their guns (if they aren’t damaged) and only loose the ability to move them (due to lack of horses), otherwise are as effective as ever.
The overall land combat interface is much improved as well. Shattered units loose their status bar and flag to make identifying active enemies easier, Generals have gained an inspire ability in addition to their anti-routing one, and in general the game has been improved in many small ways. I could list all the new buildings, improvements et all, but you should buy this game. One wonderful improvement is the ability of units to replenish lost soldier passively within friendly territory. This eliminated the costly pay to replenish that didn’t work very well in empire.
I’ll have more later, but I am busy thoroughly enjoying Napoleon Total War. Have fun