Yeah there are alot of great enemies that they didn't use but damn it I wish they would've!hey i just beat hell and hell and it unlocks some concept art of enemies. normally this wouldnt be a big deal at all but none of the enemies appear in game, however some we have already seen but in Vergils Downfall such as the behemoth demon. so this makes me think some of these enemieswill be in VD as well.
Note: one of the enemies in particular looked sooooo cool it looked an angel from Evangelion O.O
Alot of them look cooler than the ones in the game.