Zone13 was designed mainly for net doom play, though it is large enough to be a good single play level (I included a hidden exit.) The level has all the weapons in multi-player mode and a good variety of items, in single player form there's plenty o' monster-wasting to be had.
Aside from a couple of stinkers (I'm looking at you, maps 20 and 33), this was a pretty fun and challenging map set to play through. For the time limit imposed in order to make these maps, they're of pretty nice quality, I think. While I wasn't the biggest fan of the (in my opinion) overusage of Arch-Viles and Revenants, it was still a fair challenge.
Disregard earlier review server error caused me to download the incorrect file.
So what do I like? The textures combined with the sharp lighting contrast between heavy dark and rather bright areas. What I don't like is the rather empty feeling level with large rooms and corridors filled with medium tier enemies on Ultra Violence, i.e cacodemons and hellknights, while only given a shotgun and chaingun. The issue with this is that encounters become more tedious than dangerous. I would add a super shotgun or spread out the medium tier enemy placement. The level detailing leaves a lot to be desired with the large empty grey rooms/corridors reminding me more of Half-Life than Doom.
With some more detailing and better monster/weapon placement I would rank this higher but as it stands this level leaves a lot to be desired.