This is probably a bit late, but as I don't get to play as much as I want to, this is my first impression of the province system and I love it!

In my Suebi campaign I own 4 to 5 provinces and finally have the money and technology to build the third to fourth tier buildings. I've never had this much fun just tinkering around with my buildings in any previous Total War title. I'm trying out different specializations trying to get as close as possible to my happy cap and reducing my food surplus, which was around 30 at one time, to get more money. Now I've raised my income by 3000 to 4000 just by shuffling buildings around. It's really fun to discover all the synergies between the different kind of buildings, find the right shrine to go with it and not have food or happiness problems. There's just so many buildings to choose from and this has added a whole new scope to the game for me.

Also the Unique Ability of the Suebi to get happiness from war declarations plays into this very nicely as well. I declared several wars and declared on enemies where I don't intend to attack just to retain the happiness level back home. Gotta love those blood-thirsty Barbarians!