It took me a total of 48 hours to conquer China with an absolute military victory.
Three Kingdoms brings another iteration in diplomacy, and it is really appreciated, this time they got it right lads, you can see what the other party wants and how much of it they want, making diplomacy and relations with other factions essential if you want to succeed on your conquest.
Heroes are a nice addition, although some times they are extremely resilient (especially on legendary) they are very satisfactory to play with; their huge tree of abilities and the 4 different types of heroes bring something to the mix that is unique and fresh. This TW is very focused on relations and your champions.
Buildings and cities are also very tactical, providing a huuuuge tree of buildings from the very beginning, you have to take in account what are your available resources, what are the provinces ups and downs and how to take max profit from it. (Although military buildings have 0 to none use in this one)
Technologies are now reforms and they appear on a tree, which I may add, is super beautiful and blossoms in the direction of your chosen reform. Unlocking units are also included in this tree.
Agents are now gone and they are substituted by Champions and Spies. You can hire spies and build undercover networks in enemy factions and becoming a general or even being hired as a noble in their court, they are very useful for military actions. Characters (Champions) can also do actions such as assignments or being administrator, which provide bonuses to your provinces or debuffs to enemy provinces.
Combat is really good, only complaint is the archer AI, which is pretty buggy in close range, other than that everything works perfectly and manually aiming trebuchets is the most gratifying thing I have ever done on a total war.
I don't think I am leaving anything out, all in all it is a very complex game that will require you to learn a lot during the first turns, if you are an all time fan of TW you should buy it.