The only thing I don't like is that the computer gets immense honour guards without holding much provinces at all, then you have for example two units of raptors, a defiler, obliterator, sorcerer and several cultists along with a smathering of marines assaulkting your base right when you arrive at a province under conflict. The computer really likes to rush early, especially as Chaos and Orks. Gorgutz against a xv-15 stealth team and a Tau Commander, it's pretty easy to predict the outcome.
Furthermore, once every province goes over 6 in their defence value, each new victory becomes sludgefest that can last over 2 hours, since the two enemy bases keep spewing out high tier units non-stop and you can hardly stop them while trying to desperately build up your defences. It's challenging, yeah, but get pretty tedious soon and if you don't have a decent-sized honour guard soon in the campaign, most of the province battles with over 6 defence rating become almost impossible. I'm stuck in a Tau campaign, becase I just can't beat Chaos with it's gigantic honour guard and a 6+ provinces. And I'm only 16 turns in.