Dont care, but it's a step up from the emotionless drones from Civ 4.
The AI should be like little kids in a playground, if Timmy shoves little Jimmy, the rest of the kids should be wary of Timmy and yell "I'm telling!". Civ 4 had those same kids but on valium ("that's not too bad... get over it Jimmy, we are from different religions") Civ 3 had group of kids who traded their techs at cost among each other and stepped all over your territory, even though you spat on it before and named it Orsonland and continuously told them you were going to punch them if they kept doing, but they did it anyways but you didn't wanted to punch them because then they were going to raid all the stuff you've built in the sandbox. Stupid stupid stupid Ted, how many times do I have to tell you?, and what happened to my dinosaur Ted?, I'm telling!
But yeah, It's a step up... it's bad that it's near useless for the player though. It's like an invitation for other Civs to be hostile whenever you do it.
The problem is that the AI's reasons (or the reasons that are displayed) are utterly irrational. Again plugging it but if you search 'What would Ghandi do', a mod which has been spent looking at AI interactions with the player, you'll see a lot of examples where:
1: The AI's reasoning in the interface is bizzare and ruins immersion (You join in with a war with them and you take 1 or 2 cities. NOW YOU'RE A WARMONGER AND YOUR WAR ALLY HATES YOU! A major civ and his satelite CSes declare on you. In retaliation you take the opportunity to kill the CSes on your border. Now you're a threat to the world!). How is this sensible? I can accept them looking at demographics and seeing you running away with the #1 places as a definate and sensible ploy to tie you down with a dogpile, but the way its conveyed is stupid. And quite often you aren't leading in demographics, you're on equal heading.
2: The AI totally misjudges what you are doing (Turns in, having an AI BELIEVE that you are going for the same victory condition when you don't have any clue yourself is damned stupid)
3: Chain denouncing is stupid and it happens frequently. Not only that but it's often irreversable. When your closest ally denounces you, the world is sure to follow.
At the end of the day people aren't going to like this because they don't have enough control over the proceedings in diplomacy. in CivIV we relied on the standard flavours for each leaderhead to give us an idea of who to ally with and how to deal with them. Triangle diplomacy with characters who put low importance on witholding tech trades (Mansa Musa) were often favoured by a lot of players, and most players would try to exclude traditional warmongers (Shaka, Montezuma) from trading circles by sullying their reputation, declaring war and removing them from the game or making sure they were at war for 3/4 of the game with someone who could tank their troops or who was just as bloodythirsty as they were (which was rare, since even the warmongers had hidden respect bonuses for each other)
Civ5 has changed this to try and make the AI's generally more aware of victory conditions, but now they often come across as stupider than ever because the AI can't handle this abstract with the way they've been coded, and the AI aren't making sense to the player either as a result. Many a game I've played only to at least have one or two 'what the feck' moments fly out of left field from one AI's ball court to totally turn world events on their head for the sake of it. And as a player it just makes me laugh.
The only consistent and fairly competent AI I've seen in my games is Genghis. The guy takes no bull and regularly dagger DoW's the player at the best possible moment. He fights wars on his own terms and fights neighbours close to him, while trading from afar. That in my opinion is competent play, especially if I was playing a military game like him.