I did not have time to get into all features in detail but until now all plays quite well. Creative Assembly reduced the (financial) risk by producing a remake of their first Total War game.
Almost everything in this game was already tried out in previous Total war games but now it is all put together (and rather well I must admit).
As the detail of the graphics were increased considerable I feared slow(er) framerates than the previous title (with my I5 PC) but everything runs smoothly. Only on the campaign map I've noticed some choppy movements of units when more and more of the (strategic) map is revealed. A smooth gameplay on the battlefield is however the most important for a real time war game and until now I encountered no issues with that.
The game is improved in almost every field. The campaign map is 3D and can now fully rotate. The map was designed with much eye for detail (dark weather/rough seas in wintertime, bright weather/calm seas in summertime or the Japanese with hand carts pushing goods but nicely pass each other on the roads, not going through each other like in some other games, etc.). The family tree is back with the possibilty to marry into another clan.
The siege castles can be very huge with multiple rings of defenses.
The sea battles - although in my view also based on the same graphical engine as Napoleon Total War - are quite different as the ships are more floating wooden castles designed to board (well) other floating wooden castles.
There are some new features to Total War such as a data log showing all events in Japan, the user selectable RPG parameters for generals and strategic units (assassins, priests,...) and the victory locations on the battlefield but most things we have seen before (but now in the most advanced Total War game).
I suspect that some of the new features were "borrowed" from other games like the (victory) locations on the battlefield (comparable to King Arthur) providing extra bonusses for your troops. Why not? Ideas which have proven to work in other games should be used to make your own game better. I bet Total War inspired other games designers too.
The battlefield has not changed too much. In my opinion they did not use a different game engine than the one which was used for Empire and Napoleon Total War. How do I know? Well the grahpical issues which I sometimes had after spending quite a few hours of play during Empire/Napoleon (like the bright white uniforms for all troops on the battlfield or the black artifacts) are there again. These are minor issues though as the graphics are still state of the art.
The AI is improved (although it will never match a human). I did however surprise me once during a siege of my stronghold. Some of their troops apparently sneaked up from a backward direction into my stronghold while I was harassing the main body of their army with my cavalry bowmen (which needed a lot personal attention to avoid them being decimated by spearmen).
I did not yet try the multiplayer aspect of the game but it looks interesting.
In my view Total War has the best game concept (strategic turn based and tactical real time) of all wargames and until now the Creative Assembly is the best in this field in terms of graphics and gameplay although the competition is there and is getting closer (good for us).
All in all a very enjoyable and high quality game although I prefer the Napoleonic (and later) era. I hope they will once make a WWI or WWII Total War. But this is unkown terrain for the Creative Assembly and therefore poses a much higher risk than the proven grounds of the Medieval era being it in Japan or in Europe.
Nevertheless a must buyer for every strategy and wargame fan