Probably you already took a look on torchlight but nevertheless here are two gameplay vids: http://www.pcgames.de/aid,698252/Torchlight-So-spielt-sich-der-ueberraschend-gute-Diablo-Klon-Videos-und-Bilder/PC/Video/

The AI seems really simple to me but well working.
I like the clear style they developed without using any shaders^^
The vids gave me some motivation to continue working on my prototype too but I have to learn history for tomorrow...evil school-always interferes with my education