He really often leaves artifacts and resources untouched (even after killing the monsters guarding those artifacts)... I mean, over a couple of weeks he might eventually pick them up, but why not do it immediately?
What's annoying is that "black areas" don't exist for the AI... when watching his moves, you get the feeling that he is perfectly aware of the location of all objects on the map... this sucks... it was different in 3...
And I'm fed up with him constantly sitting in the Castle...
P.S. Don't even get me started on the army deployment before battle...