I pretty much expected this. RTS AI actually being able to compete with a MP experienced player without use of just unfair amounts of resource bonuses or abilities not accessible to the player is unheard of.
The issue with Relic games is that the AI has to be micro-managed a lot more. Other games can get by programming in macro elements and autocasting of abilities.
I've only played the first two missions (The tutorial + defensive mission) and I found the defensive mission to be fairly difficult if you do not use the artillery "get out of jail free" card.
Then again, I only had 1 AT gun.