I think about a third of them are very good, and but there are quite a few mediocre or multiplayer-only ones. I put together a 40-odd level mission with what I thought were all the good singleplayer ones.
You're probably thinking of Corkscrew, which is probably the most complex level in that pack. D1 didn't have switches and only had pass-through triggers, so it can be hard to figure out what you're supposed to do. Some of my favorites are Gamefreak's Realm, Apple Pie, Operation Res-Q and Turncoat. The Cycloid is another good D1 level, which is not part of that collection but has a pretty unique design.