Anyway, I didn't find any bugs, although I played through E1 and have some comments:
-I'm not as intimately familiar with the E3/E4 levels as I am the E1 and E2, so I got lost a couple times in some of them and couldn't figure out what I was supposed to do. I guess this is my fault though.
-IMO, this thing is not balanced towards HMP difficulty at all. I usually play on that difficulty but thought it was pretty tough for that, especially in E1M2, so I checked it out and actually found NO meaningful difference between HMP and UV--the pit of shotgunners & zombiemen, the Imp closet in the dark room, the shotgunners at the end--all EXACTLY the same in HMP and UV. They could deal with some toning down for the middle difficulty.
-Similarly, this might just be me but I HATE any time there's a big maze that's also enshrouded in darkness filled with Imps. I hated it in E1M2, and I've hated it in every map since. Throw the light amp goggles in the level somewhere--they're an underused powerup as it is!
-The lines for the central "room" in E1M8 should have "block monster" lines on the outside, preventing the Barons from getting in. Several times, I found myself thinking I'd killed all of them, only to find one or two (or three!) wandering around the rooms inside, and let me tell you--it's NOT fun to fight Barons with a rocket launcher in an enclosed space. (I would have used another weapon, but on a pistol start, there are no other weapons.) Blocking monsters from getting in there would also keep the Pinkies in there, but everyone is going to kill all of them before they get out to the Barons anyway. I also agree that it's difficult to know where the exit is after you kill them all.
Now, I won't claim to be the best Doom player in the world, but I think the opinion of "lesser" players should always be considered. After all, the original game had difficulty levels and pretty drastically altered the monster layouts for each.
I'm about to play through E2 now, so here's hoping I have less trouble with that.