This is my favourite since Medieval 2
The campaign is well paced, full of colourful characters and amusing mechanics and events. The resource system should have been done earlier. It completely changed the way I play. I'm not sure if barter is broken but I'm having a lot of fun tweaking numbers and making deals. I spent more time in the diplomacy screen in three days than in the last 10 years of Total War.
The battles feel fresh again. I was BTFO really bad at first. Situational combat bonuses are more important than ever. The units are surprisingly fast, responsive and versatile. You can't use the default meat grinder tactics of previous historical games and you can't rely on cavalry and artillery. The battle maps are better than anything before and for the first time the AI is sort of competent. It doesn't take baits and it responds well to troop movements. Using religion and agents to mess with the AI before battles is basically obligatory now.
For the first time ever, mounting a siege doesn't feel like a waste of time. There's no artillery or complex machinery - just some dudes with ladders and shitty battering rams. Walls are a big fucking deal - the guys manning them are deadly, the towers are equipped with MG 42s and then you have a vicious city map to navigate. On the other hand, now it only takes a couple of turns until the defenders start getting hungry or are forced out.
Marketing did a bad job - this is Bronze Age Total War whose main campaign sticks to the characters and general beats of the Epic Cycle.