REALLY glad you've enjoyed - most - of my MegaWAD. Surprised that, as a whole, you consider so good. Also thanx for all the negative feedback - hopefully, Episode 4 and Doom II: Damnation will turn out a lot better.
Some small notes:
#1: I consider the raising/lowering platform maze in E2M2 to be the worst part of the Wad. I really need to alter it someday.........
#2:I find it strange how you thought E2M4 was scary, and didn't mention that in E3M3 - I tried to make it as scary as possible.
#3: Since I pretty much hate Slaughtermaps myself, I haven't really created any to be honest. E2M7 (one of my personal favorites) is more like a "never stop moving" map, and E3M6 is Slaughtermap...ish.
#4: I ADMIT MY SIN - I'M A DEHACKED MORON!!!
#5: I find it strange that texturing/alignment is the biggest complain here. While I'm pretty sure there are lots of flawed parts, I really tried hard to fix most of them (especially in episodes 2-3). Unless you count the vast amounts of deliberate miss-alignments as ugly... which is the reason why you are allergic to E3M7: Event Horizon :D