Hello,
the first thing I noticed is that the bots never capture tech buildings.
The second thing is that the AI playing with NOD seems much weaker in skirmish than the AI playing with GDI. In every match NOD is put to the defensive and is overwhelmed by GDI, so that everything plays in front of NOD's base. (Maybe this is not a problem with AI itself, but with gamebalance in general)
In my opinion the AI plays really good. You can have some fine matches against them, but the bots need more coordination when attacking bases (Stealth actions and planting beacons in buildings are completely missing) to create more surprising changes during the match.