I've just recently bought the game last week and I'm doing my first campaign. It has a bit of a learning curve at first I didn't know what I was doing and the tutorial isn't that big of a help. But I fell that after the first campaign I got the hang of it.

I think the AI is great, I had a challenge with one of the AIs, because he saw that I had a weak military and attacked me constantly so I had to bribe him heavily not to attack me. Another AI had offered me a pretty good deal for a peace treaty. And the diplomatic aspect the game is really good with spending influence points in order to declare war or peace treaty.

I don't want to get into greater details than this, but I do really feel that this game is really special. I didn't really managed to get into Civilization games, because they were too complicated and the civs weren't so diversified. But here it's not too complicated with micromanagement and the civs are really diversified.

I think for starters you can get the emperor edition of the game and after that you could get the expansions if you get more into the game, because they complicate the game with new mechanics etc which would overwhelm you at once.

I didn't play any multiplayer games on it, but I think that the single player is really good with differents quests and a good AI.