The AI plays rather well. In the short time ive been playing the game they have taken me down without fail. And they do give you chances to be friendly with the missions they occasionally dish out. I havent gone near hard yet so i cant say how aggressive they are then, but they have taken out my attacking fleets easily enough and quickly decimated any unguarded colonies i put up on normal.

I came to soase from GalCiv 2 also, and the ai compares very well. Allies are actually helpful, and enemies like to fight.

The AI is pretty good. Unfortunately it won't fight you unless it is sure of a victory, so most of your time is spent chasing them in circles around solar systems. They need to change that about the AI.

I've played four games solo against the computer. One alone and three with an AI buddy, and I agree with everything that's being said.
1) Bot opponents won't hesitate to hurt you. You have to be able to split your fleet and manage a roving defense.
2) Bot allies haven't been great at direct intervention (e.g. they show up when my planet's getting whacked), but I've noticed a definite willingness to pile on! So, if I am launching an attack I am not surprise to see my AI buddy show up a little while later and join the fracas. Allies also seem adept and carrying their weight - expanding and distracting some of the opposition. One interesting whisper I got from the bot was something to the effect of, "Go pound on the homeworld of the guy who's pummeling me!"
3) It is difficult to force an engagement when the bot is outgunned. While this makes tactical sense, from a playability perspective it means that there is no war of attrition or pause between harassing raids. You chase them away and as soon you leave they come right back at no real expense since nothing (much) needed to be rebuilt. There are some technologies that allow you to slow down departing fleets, but a) 3 out of the 4 games I played were decided before that tech really made sense to pursue, and there is opposing tech that cancels it out. But, it might be possible in larger/longer games to create a sort of "tarpit" or "roach motel" system with lots of phase inhibitors and a waiting nearby fleet...

About that, do phase inhibitors effect stack? You're talking about the buildings with area of effect right? i was considering building a few of those together but i though the effect wouldnt be added

I've been playing 3v3 on Maelstrom a lot the past few days, with locked teams so I don't have to deal with the inane missions, and all AI set on hard random. In every game, each AI masses two fleets, one with just a ton of siege frigates, and the other with just a ton of the basic attack frigate and some cap ships. This occurs the entire match, even when I'm roving around with an uber-fleet of 100+ ships. So... I'd say the AI still has a lot of work to be done. But I have faith in the devs - just wish the AI was more sophisticated from day one.