Played the PC demo, my impressions were the following:
+) Decent graphics with at least 8X AF turned on, really helps clean up the sometimes uneven texturing. Nicely animated world, very vibrant and colorful without being drowned in a sea of pastel colored, Miyamoto-gone-wild senility. As with all decent 360 ports, nice use of shaders. No real graphics configuration features outside of low/medium/high and resolution, but that's not a big deal.
+) Amusing, Dungeon-Keeper like "so good to be so evil" vibe delivered properly. Minions do funny things, burning halflings alive is entertaining too.
+) Mouse and keyboard controls seem fine and work well. 360 gamepad works just fine with zero need for configuration.
-) Demo level design was very linear and claustrophobic.
-) Core game play seems to be extremely brain dead and simple-move around, send demons at stuff, stuff gets done, you get reward. Before anyone complains about too much reductionism in that description, it really is all that is there. Too much ripping off of Pikmin (console faggotry) and not enough of the game they should have taken ideas from (Shiny's Sacrifice).
Maybe the full retail of the game has more depth than that, but I'll wait to read a review from someone I can trust (read: a veteran PC reviewer and not some fanboy on XBOXAchievmentPower.com or some shit) to see if they rail on the game's over simplicity or if my taken is just the artifact of Codemasters' poor choice of a demo level that doesn't show off the gameplay well.