I'm going to regret this...Leap of faith - bought the game...
I've played about five hourse so far, and.....
Hmmmmm.
Things are different enough from Civ 5 to require a little adjustment. I miss all the mods I always play with, so I was struck at first by what are limited game setup options, although Civ 5 was the same way IIRC.
Have not seen anything that I just absolutely love, though, and I am struck with how "cartoon-ish" a lot of the elements are, especially the appearance of the civ leaders. Sort of feels like a step back, like this is "Civ Junior" None of the youtube videos I watched conveyed how much of an effect this is, YMMV.
AI seems to be about as irrational as ever. Playing as Teddy Roosevelt on a Huge Continents map, was at war with Germany, and was on the verge of losing a city when he just up and pulls back. I first thought maybe it was Cleopatra attacking from his other side, but then three turns later he's back at it. That went on for about fifteen turns, and it enabled me to fight it out and get equal-terms peace treaty.
Interaction with city-states is remarkably different, I think I am going to like it in that regard. One thing that has always annoyed me in Civ5 is the constant requests by one on them to wipe another of them. That makes me thing about the absurd "warmongering" penalty, which I hope has gone away this time.
It's not "love at first sight", but when Civ 5 first came out I couldn't figure out why anyone would want to play it instead of Civ4, so we'll see.