it turns out Eternal made a second map last year, aside from Frozen Time. This is one of his "working under a restriction" maps like 32 Inch Nails or the 2x2 texture series - in fact it's basically the former with double the grid size restriction. Every vertex is on a 64x64 grid, which makes for some rather large architecture.
Other than that it doesn't look too dissimilar from several other of the author's maps, using his preferred set of textures, mapping techniques and so forth; many prolific map designers have a distinctive style. I did notice one error in the texturing: looking east out of the BFG room, behind two trees there is a large, noticable "hole" where sky should be under the upper ledge. Since it is rather large I wonder if it only appears in software mode (I wouldn't be surprised if Eternal and entryway only tested the map in OpenGL)
As for how it plays, there are two or three large chambers, one of which has high walkways round its edge, some corridors, the usual sort of thing for a castle / fortress map. The ledges have to be traversed in the latter part of the map, and if you fall off you have to go all the way around the map again, which was a bit annoying, and before that the revenants on said ledges just have to be hidden from. Secrets are plentiful, and one thing you will notice is that there is no health in the map other than megaspheres in secrets, so you will probably have to find at least a few of them. Fortunately they are not hard to find, especially if you are already familiar with the author's mapping style. Just look for switches on walls and sides of pillars that aren't in view of the whole room.
From Dutch Devil comes the sequel to 2010's Evil Unleashed, in much the same style: E1-ish techbase, set amongst natural rock formations, with a hellish ending.
It's more straightforward than the original, and in particular there's no point in the middle where you have to run halfway round an empty map. On the other hand it does seem a bit more disjoint. There are also no large monster teleporters; there is one place where, based on the style of the original, it looks like there is going to be a massive warp-in, but all it produces is a single baron, and that, when you are nowhere near the destination, so you don't actually hear it come in, you just walk into it later.
Other than that there's not really a lot to say. I mean, it's a good map and worth playing but not much memorably stands out enough to get mentioned in review. This is probably a good thing, though. Things that stand out tend to be things that I've found fault with, so there can't be any huge faults.
Oh, wait, one thing: I spent ages trying to figure out how to get into the curious little room visible through a window opposite the ledge the blue key is on. When you see this you might find yourself trying to strafejump and stuff to get over there, but don't bother, it turns out it's just decoration.