Reconsideration: I played La Ciudadela again and it's grown on me. It might not look much but it's wide open and you can run about doing what the hell you like. Of course you might die if you take the wrong order but working out the right order is what makes it fun. Too many maps feel like you're just being led through situations the author laid out for you.
PN Slime Base In some ways, the citadel's opposite. Made by a modern map editor, so architecture and texturing are flawless, as you'd expect when the program does it all for you. Nevertheless it's still just a sequence of small areas which you clear out one at a time, and move on; when you're done with each one, it might as well no longer exist. I find this kind of gameplay uninspiring. The one highlight was "give the player a rocket launcher then throw 30 imps at him".
Grid 32 For something completely different, we have here another of those restricted mapping challenge wads. This time it's "use a grid setting of 32", obviously enough. It looks nice enough. The architecture is cool even with the restriction, in fact I think a lot of Doom's textures work better if you keep this kind of grid size, but in general I found the gameplay to be quite cramped and low on ammunition, and the wad ended up annoying me. The first level being based on the most irritating map from Deus Vult II and, worse, completely disabling the automap, didn't help. However I will try again on a lower-than-UV skill because the maps are decent, at least.