To me, MOST of DooM II's maps are kinda' ass. Not that some of them aren't fun, but they all kind of feel like a clusterfuck. I suppose it's easy for me to say now, since anyone can just toss out a map these days in a matter of hours, if not minutes, with DooM Builder.
Still, I remember using DooM editing and mapping software for Windows 3. I got as far as making one arena, with no real understanding of how it all worked, so I still feel like DooM II was kind of slapdash in its construction.