Well, I was going to make a post agreeing with the people saying the AI is too peaceful but then I played 200 turns of a new game. The two games I've played so far have gone completely different:
First one, multiplayer/shuffle/small/quick:
Civs were: Spain(me),Germany(friend of mine), America,Mongolia,Persia,Iroquois
There wasn't one war until about 1850AD, and both my friend and I declared it(on Washington). Each civ pretty much had it's own continent and we all had very profitable sea trade routes with one another. We went after Washington as he stopped trading with us/had a ton of tourism. I had spent the majority of the game with 2-3 early game units and I attacked with 3 Privateers, a treb, a knight, and a rush-bought Gatling. My friend distracted Washington with some crossbows shooting across a 1 tile wide channel. I met no resistance taking his capital, my friend said he shot down about 10 warriors. Even worse the CB who had been guarding Washington's capital fled when my troops landed.

After I took the cap he started producing minutemen, better late than never? Also worth noting that shooting off that war ticked off the whole world. We took one city each from Washington(the cap for me, NY for my friend) but the AI were acting like we wiped him off the map. OT: Without Barcelona I'd probably be far behind, having that city there let's me move ships around the world very quickly. Wouldn't have had much luck trading if I hadn't built there.
The second game I played changed my mind entirely.
Singleplayer/Ice Age(Wide Continents)/Large/Standard/King
Civs: Austria(Me), Songhai, Assyria, Mongolia, America, Germany, Sweden, Netherlands, Russia, and France
Here there were 4+ wars going by turn 75. Most of the AIs were ganging up on Khan as he was attacking CSs. I captured a city from the Songhai as it had Kilimanjaro in it's borders.(and it was a good choke point off my isolated part of the continent) Somehow Khan was able to hold off 6+ of Assyria's siege towers though he did get a city razed. He also managed to take a few cities from Germany while being at war with half the world. Not much later Assyria got tired of Khan and turned on Germany instead, taking Berlin and a few of the surrounding cities.
About the same time Songhai signed OB with Assyria and marched his whole army across his borders to attack Khan. Bad move on his part, I took and razed one of his cities and headed for the capital. When I noticed his troops coming back from across the map I paid Assyria to attack him, they were cut off and slaughtered.
Throughout all of this I've maintained a good trade relationship with both Khan and Assyria, and had a DoF with Assyria for most of the game. Despite the fact they could easily take me out we remain friends(because they have 4 cargo ships trading with me?), they even leave the CSs I pledged to protect alone(while conquering every other CS they meet unless Khan gets to it first) I know they know they exist as they sent a great prophet to a few of them(hey those no longer only target capitals!)
Even more surprising, I eliminated the Songhai from the game and only Sweden seems to care. It seems that they have fixed the warmongering penalty so that the AIs take into account the warmongering of the other players as well as their own attitude on it. The WC was just founded and it's mid-Ren era, this is what the map looks like ATM:
Songhai's previous capital the left-most of my cities(red color). My capital the right most.
So, it seems the AI behavior is more situational. A welcome change IMO as it means you can't plan out your game before you play it. Anything that makes the AI more unpredictable(as long as they act rationally) is an improvement IMO. In the first map I played we all had very profitable trade routes with one another, going to war would cost you 30g+ a turn. In the second the Civs are fighting as you'd expect but still maintaining good enough relations to keep their economies alive.