Yeah, they could do a lot more in it with true 3D maps, but the design was all brown. The bosses were boring - the first one is kinda cool, the others not (IIRC episodes 2 and 3 were just kind of standard enemies); all three of Doom's were scary, especially the Cyberdemon when you can hear it roaring and the noise of it walking around.

The Lovecraftian vibe could have been cool but it doesn't really come through in the game in the way the satanic / hell thing did in Doom.