Just played a game with four random "tough" AI and tech trading disabled.
AI issues I've never seen before:
Freighters. Everywhere. There's a vast cloud of somewhere between 15 and 30 freighters from one neighboring empire. They move about through my space as if looking for places to set up trade routes or something. They stick for several turns when the guy eventually declares war on me, and just a few of my basic fighting ship (a two-point missile rack and a single engine) clear them out in a couple turns.
Unarmed "Defender" Ships. I attack my nearest neighbor early. Not so fast that I'd call it a "rush," because I took some time to develop my colonies, but early. He never fired a shot, but there were about ten unarmed ships in orbit around the three planets I attacked. This struck me as a lucky break as I was hitting him early, and there's nothing unusual about catching a few scouts & constructors in orbit when you pull a sneak attack.
He surrenders readily and I keep rolling, right into the next guy, the Yor as it turns out. When I attack him, there are a total of maybe 15-25 ships in orbit around the four planets I attack. This time I pay more attention, because this is way more than just 'a scout and a constructor' in orbit. These are large stacks of ships marked "defender" that have no weapons.
We Surrender! Enemy AIs surrendered for more readily to me than I'm used to. This, however, could be because of a change in my playing style rather than in their code. In my Beta games I've been both going to war earlier and attacking more thoroughly. I used to attack slowly, making a determined and somewhat ponderous assault on one planet at a time. Now I've taken to swarming the enemy with ships, blowing up everything everywhere, and then sending in the transports while my fleets patrol his space, shooting down lone ships as he builds them.
In my one-planet-at-a-time days, an AI would wait until he was nearly finished to surrender. When I hit him everywhere, he surrenders very early, in one case surrendering at least five planets after I'd conquered just one, a tiny class-5. In this case the AI leader, when explaining himself, made specific mention of the fact that his "military [was] destroyed." Maybe this is an AI change, or maybe I've merely learned which buttons to push to convince an AI to surrender. I hope it's the latter--I hate the waste of invading planets. If AIs are likely to surrender shortly after you demonstrate total air superiority, that's pretty cool.
Issues I've seen before that continue in the beta:
[Really Dumb Building]. Okay, maybe not dumb. Maybe the AIs are attempting strategies I don't understand, or dealing with crises I can't see. Here's what I've seen when I conquer or receive planets:
1. Manufacturing/Technology capital, but no factories/research facilities. This one is pretty common, and is often accompanied by #2 below.
2. Tons of influence/morale buildings. It's not unusual to find four or five of either (and in one extreme case, each) on AI worlds.
3. No factories. I don't get this one. You just can't bootstrap a colony properly without at least one, and I always build two. Always. You'll never keep up with the simple pace of upgrading your buildings without some factories. This may be why, in the late game, I frequently take over high-value (12+) colonies that have only a handful (four isn't unusual) buildings. There he sits, 34 turns into his 150-turn build cycle on an extreme sports arena, when I invade.
GalCiv2 Forums
Feeling really dangerous tonight? We've got the BETA of v1.1 now available to download. Don't know what a beta is? Don't know if you should download this? Then don't. 
I choose to build something on my planet, it will be completed in NEVER. Well, that was very shocking. I have to either wait a turn, or try to build something after it, for the appropriate build time to display (at least it is more accurate). Also, sometimes a time is displayed but it is something outrageous like 200 turns (and of course, not accurate).