Another day, another stolen map.
E2M1 of IMMLEV is a ripoff of ARENA, a tutorial WAD David Bruni designed and wrote detailed tutorials for in the 3D Alchemy book. Walbert's edit of it was so incompetent that four times out of five it will crash vanilla seconds into the level with a "P_CrossSubsector" error. Crispy and prboom-plus crash every time.
Oddly enough, Choco loads the map without complaints but you get stuck early on due to the "author" apparently using a paper bag over the head as a map-editing tool.
The second map is largely a barebones crate maze. A secret door next to the first key leads to an unmarked exit that dumps you on the stock secret level. Too bad, as the third level finally shows a glimpse of promise, albeit somewhat marred by HOM and mislabeled key doors. This, too, is apt to an abrupt end with another unmarked exit switch.
The difficult of some maps (mainly after MAP 20) is rather extreme in UV if you aren't an experienced/very good player. For others I recommend playing in HMP or even HTNR if you don't want many frustating moments. Best maps = 04, 06, 07, 08, 11, 15, 32, 18, 20, 22, 28, 29 and 30. Bad Maps = 05, 31, 23, 25 and 26. All other maps are OK. Now, some considerations: MAP 24 is very good until the archvile spam, after that it's almost impossible to beat if you don't get the secret invulnerability sphere. MAP 26 is a gimmick map with a lot of archviles, I didn't enjoy the gameplay because if you shoot in some parts you die right away due to the sheer numbers of viles. MAP 29 at first seem very hard and frustating but its doable if played with persistance. The only bad thing about it is the mandatory archvile jump which I didn't aprove (if you play it you'll see what I'm talking about). UV maxing this MAP would be a nightmare since the red key area is very hard; I've yet to see anyone at youtube or twitch UV maxing this map without saves. As I think only 5 MAPS out of 32 are bad it deserves at least 4 stars.