Having spent way too much time in this map than any sane, normal person should, allow me to list the good and the bad of this map, and "why does it get so much dislike?"
- The detailing in this map is above the bar. Having the slime actually fill up the reservoir is a really cool, unique touch that makes an imprint upon the memory when you think of this map.
- Also on the detailing, that multi-sectioned lowering wall thing that is right at the run to the exit. The one surrounded by Specters with the Berserk/Invuln. Really cool job there I must say. Pushing the engine to it's limits and again, leaving that nice impact of something neat you'll remember.
- Having a secret INSIDE of the actual part tagged as the exit was something memorable. No other map in Doom, Doom 2, and Final Doom, pull this off. That is, if memory serves me correctly. This gives it a unique way of sending you off to the next map that you'll remember.
- You don't need any keys to finish this map, making it easy to just skip the whole thing if you choose.
...that's... that's about it.
- The hallways are a jumbled mess. Sure, the detail on the bottom sides of them are neat with the "stair" effect, but actually USING it as part of a door to get into the rest of the tunnels is ridiculous. The doors in the pipe maze are horribly designed. You have to cross two separate linedefs to open the one door, only to have half of it slap shut in your face because a Specter or Shotgunner got in your way. It's awful.
- Secrets are so far out of the way and so badly placed that you will probably miss at least one most of the time. To make that worse, the secrets are areas of the map that are, again, out of the way to reach. Each one is tagged to open by a linedef that's a complete inconvenience to get to. Add that it will most likely be in a place you won't be looking. The Soulsphere is about the only 'good' secret in the map.
- No solid theme. We go from tunnels to the outdoors, sure, that's fine. However, including that blue underground area and the crates seem out of place. The rocky portion of the tunnels could work with the outdoor nature this map gives off if it wasn't for the...
- ...bad texture combinations. That repeating white light on the wall gets pretty annoying to look at after a while when in combination of the rocky textures above and below. Also, why is there a liquid texture in the ceiling of the tunnels? Never could figure that one out. The random slime textures seem a little out of place, despite the touch it gives when it fills that reservoir toward the end. Looking down long hallways with those particular textures can strain the eyes, too.
- Combat in the map is spaced out and not very fun. Boring is a good word. You are running through 90-degree-turning-hallway after 90-degree-turning-hallway and shooting Shotgunners. The occasional Specter and Zombieman. Mostly Shotgunners. All 48 of them are in the tunnels, giving them almost no monster versatility. Even the outdoor parts aren't interesting in combat. A wide-open Arch-Vile with some Hell Knights on a hill is about as interesting as it gets, and that's still boring.
Now that I've covered all of this, let me give you the absolute #1 reason this map DESERVES the dislike that it gets: If you are playing the map on Nightmare or -respawn and you even TOUCH the tunnels, good luck finishing the map. You'll almost consistently crash out of vanilla Doom with a "no more flats!" error.
This is obviously an issue that's exclusive to the old DOS Doom since source ports have removed limits and won't crash at something like this. Yet, take a step back and think about it. This was released for Doom before source ports were a 'thing'. Nightmare isn't something normally played, and neither is -respawn. However the point is that this map will consistently crash the game under these circumstances because there is *too much detail* in the map. Too much going on at one time. This is something officially released. This is an official map. All things considered, this is a rather large flaw to have in a map that's "official" and such.
As ironic of a statement as this is considering how dull and boring the map is, the amount of detail ends up being it's nail in the coffin. All of the detail is in the wrong places. The good details are in bad places or are part of bad ideas, and all the bad details stand out like a sore thumb.
There is nothing about the map that can be redeemed, it teaches you nothing if you rush to the exit, the combat is boring, uneventful, and repetitive. Sections of the map make absolutely no sense (considering that TeamTNT was going for a more realistic approach).
No, on second thought, there is one redeeming factor that might provide the *only* reasonable argument this map has in opposition of it being the worst map in the game.
You don't need any keys and don't even have to fight any enemies to finish the map.
Hopefully I've provided at least a detailed view of why this map is the worst map in TNT... and could very well be the worst officially released Doom map to date.