My first impressions:
Played a fairly normal game: Byzantium/Theodora, Standard size, Continents Plus (so all the city states are on islands off of the main continents), Normal speed. Prince difficulty.
Austria and the Netherlands were on the same continent as me, but the Netherlands grew wary of my cities near their border and asked me to stop settling near them. I agreed and after about 20-30 turns a message popped up saying that I had now fulfilled their request. Granted, I still got the negative diplomacy attitude of "They covet your lands," but nothing negative related to the promise to not settle near them.
As for religion, I went with Buddhism and a Pantheon belief that gave me production from fishing boats, as I had lots of crabs.
Religion really does drive your future settlement considerations as you think about ways to leverage your pantheon abilities. I went straight to settling coastal cities as I knew that I could get that benefit.
Maybe other reviewers can bear this out, but there seems to be a difference between civs
keeping their own religion and
spreading it to others. I found that Maria Theresa never sent a Hindu missionary to either William or me - any Hindus in my lands were there because of city pressure. She did use inquisitors to remove Buddhists from her capital and other cities as well. Conversely, I later met Boudica on another continent, and she had spread Confucianism far and wide to two other civilizations as well as two city states. Perhaps some civs are satisfied with leveraging their own religion while others seek to convince you of their awesomeness?
The AI is much better and defending tactically, though strategically it can still be a bit lacking. William successfully repelled two waves of my attacks on Amsterdam,
making sure to pick off the most wounded of my troops, but he had only placed two or three units at Utrecht, despite knowing full well that most of my troops were there with his message of "I see your troops..." Navally, the AI also focused down my weaker embarked units instead of attacking my powerful dromons.
Small notes:
- My missionary that was captured by barbarians stayed a missionary when I recaptured him. He didn't turn into a worker or something, thankfully.
- Missionaries can even spread religion while embarked. (Say, to a 1-tile island city state)
- AIs only get pissed off at you if they founded their own religion and you're trying to supplant that. Though the Netherlands did not like me (as he had DoW'ed me) he and Sweden both accepted Buddhism without any problems as they didn't even have a pantheon. Hindu Austria on the other hand actively purged their cities of Buddhists each time new ones popped up in their cities.
- Some city-states have "project" quests, in which gold gifts give 20% or so more influence. It lasts for about 20 turns and is similar in effect to one of the starting social policies in the Patronage tree.
- Units gifted by friendly militaristic city states now are delivered directly to the closest tile owned by you. This is probably because open borders are much harder to get now, requiring an Embassy and correct me if I'm wrong, Civil Service. It's fairly late especially compared to the earlier unlock at Writing. It's a nice improvement over having to transport them over an ocean or mountains.
- I'm not sure, but it seems that Friendships are now more "durable" than before. I wiped out the Netherlands from the map, an action in vanilla Civ V that would usually result in whatever friends I had denouncing me, saying that it was a mistake to work with me. Not so in this run through - my friends Sweden and Carthage had no new negative attitudes towards me, though the antagonistic Ethiopia started to see me as a war-mongering menace.