I played as Britain on very hard and have it all locked up about 35 turns in right now.
The AI essentially did nothing and never mounted one amphibious assault anywhere.
France allowed me to occupy Holland and Brussels indefinitely with no response.
None of the other powers expanded colonially.

The Cherokee were the only faction that fought hard and continued to send large stacks at my American colonies until they were defeated.

The AI can be manipulated into agreeing too easily to peace after a defeat. This allows
you to absorb a territory, replenish your troops and then attack your weaker opponent.
Not to mention that the large amount of factions makes diplomacy tedious and other nations
won't enter into alliances with you.

Did CA even bother to script a set series of moves to guide the AI? Or prioritize certain areas to attack and defend? It seems like the AI just sits there and gets its ass kicked.

If you recall in MTWII when playing as Venice, Sicily would always attack the balkans by amphibious assault after 3 or 4 turns. Predictable, but at least the AI had some kind of gameplan and was capable
of loading troops onto a transport.

It appears that the campaign AI in this game is actually worse than MTWII, which was basically unplayable out of the box.