Enjoyable to play and behold all throughout! Great use of the moving Ironwail skyboxes, awesome atmosphere. Very clever reuse and repopulation of the maps without getting confusing. I'd say dmd3 was the only map where I was quite never able to fully internalize the layout of the level, and when I was "endgame" secret hunting, I had trouble finding my way to some particular rooms I wanted to explore.
The maps also got predictable in some ways, like you could almost always count on monsters appearing upon picking up keys and whatnot. Also, there was a lot of spawning shamblers in pairs. I figured the idea was to make it harder for the player to cheese the monster, but in nightmare difficulty, due to the change in the monster's behaviour, more often than not, they ended up being cheesed pretty easily regardless. So, these shambler fights often felt more tedious than challenging.
I've yet to play the campaign on hard, which would probably alleviate the dual shambler issue, but regardless, these relatively little issues aside, it's an excellent episode that I would include among the must-plays of custom Quake content. I'd rate the map maybe around 4.9/5 or 4.95/5. Very specific, I know, but hey, that's my gut feeling, a very specific gut feeling.