A step up from the Master Levels for Doom II (which I understand were designed by completely different people, so I only mean to imply my relative opinion of quality, not some kind of iteration between the two entries). Not every map seems inclined to use all three keys, which is a shocking amount of restraint. Few levels run into the "where the hell do I go next" problem, but it does come up in the back half a few times.
Did wad-makers ever learn consistency in conveyance? At times, interacting with a colored gate does nothing, because you're meant to interact with a color-coded switch somewhere else in the level. But at least a few times I was stumbling around looking for such a switch, only to find that the colored gate WAS interactable this time. It seems like within a single wad, there should be consistency about that. Also, consistency about which floor textures damage you or not, because that's a total crapshoot depending on the level.