I think the A.I starts pretty well but generally starts to fall behind mid game.I get the impression they dont migrate pops around their empire which I think most players have mega farm worlds where they just maximise planets.

I also notice they are not getting trade routes up until far too late and hording resources so they have a lot less dust than they should.I have seen them with 600+ or so late game strategic resources that would fund 5 fleets in a pinch.

A lot of this could be solved by tweaking.I think some scripted actions for important techs and their racial strengths would improve the A.I faily easily.

They also leave pirates alone for too long.They have the fleet power but seem to hardly invade bases.

The A.I is lot better but I feel mid to late game they lose steam and the game does too.Endgame is lot of pressing turns for most victory condition because you know it's over.

Did a few games lately and i do agree, the AI, while good in many respect, still fail in micro-managing it's stuff. 

In my last game I saw some impressive AI fleets including all sorts of ship classes and they were used quite well (I had to adapt my tactics and layouts way more often then in earlier versions). So AI has definately improved in this. But I do agree on their ignorance of pirate hideouts. In said game there were several of them in a "neutral" zone between our empire borders and over the whole game I saw only one AI fleet (Riftborn) ever cleaning a hideout - I had to do the dirty work there most of the time.