Well, in light of "All feedback is welcome!" ... I think I'll say a few things:
First, I love it! I wish more wads were as detailed and well thought out as this. So excited you're back in the Doom saddle! Second, I give up. I've scoured every inch of the map and can't figure out how to get the last secret - the secret area that leads to your signature room. I think getting in has something to do with the combination lock puzzle, but I can't find a combination that works beyond just progressing normally. I also couldn't get the door to open to begin the BFG quest, but I think that might have to do with the broken switch...? 6/8 ain't bad! =P
Anyway, it was a great level! I can't even imagine the time it takes to weave a path back through areas you've already cleared while still keeping it interesting... like a writer lacing foreshadowing and ah-ha! moments. Some elements reminded me a lot of "The Earth Base" (like the..vestibules?..near the beginning, one holding green armor) and I love your approach to secrets. Not just wall bashing or a different texture but something physically different, or better yet, actually being able to catch a glimpse of the secret area itself, making you wonder "how do I get over there" or behind there or whatever. Secrets within secrets are also a huge plus, though I didn't see any this time around =P
Balancewise, I also found myself running out of ammo here and there, especially during the huge fight before the red key. Oh! That secret with the soul sphere..loved that ah-ha moment when I finally figured out what the switch on the reverse side of the pillar did.
Let's see.... I got lost in the area near the exit. The first time you get there you can see it needs a red key, and the only other path is a door that's blocked off. I waited and no enemies showed up and the bars never lowered. Ran the whole level and returned only to find a cacodemon waiting for me. lol!
Okay, not sure this is helping. Just wanted to say thanks for sharing the beta! I can't wait to play the final!