This is from another forum on TW, but a very good run down of what makes NTW so good and I couldn't agree more. Excellent game especially if you have a good system.
1) Generals can now rally and inspire troops on the battlefield.
2) Artillery is more deadly.
3) Units are more graphically detailed and less generic than ETW.
4) Attrition.
5) Troops now auto-replenish depending on supply lines in region. You can either be in slow, moderate, or fast resupply. Also, your units will not resupply at all in enemy regions. Its simplistic, but a step in the right direction.
6) Campaign map is more detailed and outright beautiful.
7) Campaign map has seasons which are reflected graphically on the campaign map.
8) Battle maps reflect seasons graphically as well.
9) Graphically the game looks much better than Empire in all respects. May not be as noticable on an older machine, but on my 5870 it looks outstanding.
10) Smoke effects and the destroyable environment are amazing.
11) Campaign AI is more aggressive and streamlined with a single map and in place alliances. I thought the smaller scope would be my biggest complaint, but it has actually improved gameplay in my opinion.
12) BAI is a huge improvement over ALL previous Total War games. Its not perfect, but its much better and less predictable than previous titles. And regardless of what people are dying to convince people, there are no "bugs" with the BAI.
13) The game is much more stable than ETW.
14) The game is much more polished than ETW.
15) Campaign music is great and an improvement over ETW.
16) Multiplayer campaigns.
17) Drop in battles.
18) No more generic Generals. Now all Generals are historic and have unique skins, both on the campaign map, and on the battle map.
19) Improved diplomacy...you can now ask an ally to break an alliance with a rival, request a trade embargo to be put in place with a third party nation, or allies can be persuaded to join ongoing wars.
20) Naval repairs in battle.
21) You can now change building types instead of first having to destroy the building. This is great because you can now swap a high tier building to another high tier building of a different type. Previously, you had to destroy the building, then build each tier to get to a higher level building.
22) Almost no siege battles. CA learned well from ETW and have made it highly unlikely that you will have a siege battle in NTW. They increased the cost of star forts to 8,000 and 16,000 for large star forts. I've only had 2 siege battle in the hundreds of battles I've had on the campaign map so far. This is another huge departure for a Total War game as most people quickly got tired of playing nothing but siege battles in past titles. Huge improvement. Sadly, the AI still does not handle siege battles well though.
23) Ability to liberate a region instead of outright taking it over. This is a fun addition for roleplay reasons, but also for strategic reasons like not wanting to maintain a garrison in a terrible location.
24) Unit icons on the battlefield! Another seemingly irrelevant improvement that has made locating and identifying troops much more reasonable.
25) Fire and advance looks very cool, and from what I have read, it's historically accurate. However, it doesn't work all that well and doesn't seem to give any practical advantages. It does look very cool, though.
26) Observation balloons!
27) The ability to view the enemies troop deployment prior to deploying your own troops! This is based on your General's rank. Huge improvement! Makes a huge difference if you're planning on charging the enemies artillery, or the General. I love this ability.
28) Individual soldiers now have conversations on the battlefield! Yet another feature that seems completely inane and useless, but it really adds to the experience. One of my favorite new features.
29) Spy networks.
30) Gentlemen can now cause unrest in towns.
This is all I could think of off the top of my head. I haven't enjoyed a Total War game this much since the first Medieval Total War. And I've played every single release, including expansions. This game is that good. Empire literally looks like a pile of dog **** next to NTW. If you have a new computer that can handle the game in all its glory, and you like Napoleonic warfare, you have got to play this game.