To second what Ryat says, the AI has changed considerably since Entrenchment. In fact, it changed significantly just during the update process for Rebellion as well. I like a long game and tend to play in the vast single-star environment, and the AI that I am fighting against definitely poses more of an active threat than it used to. It can not only be quite aggressive, but very stubborn on defense as well.
Having been playing space-based computer strategy games since the 1970's (that's not an exaggeration, either -- the first used to run on a Raytheon 1000, which is a computer so old you apparently can't even Google it; let's just say the 1000 referred to how many BITS of RAM it had), I am very well-acquainted with a large number of AI's. And this is probably the best, i.e. least predictable, that I have ever encountered.
