From last time: Grid32 turned out to have one good map, at least. Well, sort of. Map01, as I said, is a clone of the forest map from Deus Vult 2 - dark, no map, invisible teleporter lines, annoying as hell. Map06 was somehow worse, it's miles and miles of almost identical stone corridors and copypasted rooms. While it did seem that at least some effort had been made the basic idea was, I believe, flawed, and it was just boring to grind through.
The spider-shaped map02 was quite inventive, since much of it was not aligned with the axes. Somehow this worked despite the restriction on vertex placement. However, a certain lack of health and ammunition made it annoying, but dropping the skill level down helped. In contrast map03 - kind of an underground sewer map - was entirely 90 degree walls parallel to the axes, split into largely disjoint sections, not particularly difficult but not particularly interesting either.
I gave up on map04. It has a clever mechanism to raise and lower two bridges with one switch, but it breaks if you press the button again too quickly. The lack of health and ammo, and having to pistol my way through two imps while being attacked from behind by spectres and chaingunners just to get a shotgun, didn't help either.
The best map is map05, which a nice underground base and slime river, with lots of nice height variation, interconnection, long lines of sight etc. Unfortunately it's a ledge-running map, so it can get pretty annoying. Apart from that though the difficulty is at quite a nice level provided you know the map already (so playing it first on a lower skill level helped)
Xenus revisited is the "full" version of Xenus 1.5, and replaces Doom's episode 1 with your usual mixture of base-becoming-hell maps. Also E4M1 for some reason. As with previous wads in the series they suffer from hyperdetailed corridor syndrome. There is at least one map that isn't completable due to ZDoomisms (E1M2 has a walk trigger in front of the red door - there may be others, I can't be bothered running through the rest of the maps right now to remind myself)
It's a shame, really, the individual small parts of each level here are good, well-detailed and so forth, and there's no lack-of-resources irritation at all (in fact if anything the author goes overboard with giving you ammunition) but it's all very disjoint and maze-like, and it ends up underwhelming and unrecommendable.
For the sake of completeness there is also the original Xenus: Lost Base. Firstly it uses textures as flats, so only ZDoom will load it. If you work around that you get a fairly bland single map. It would suffer from hyperdetailed corridor syndrome if it were hyperdetailed. The most interesting thing is to see how the author has improved at detailing (a lot) avoiding ZDoomisms (getting better, needs more actual testing) and making maps with interesting layout (not much at all)
Blackout Two maps in your usual abandoned where's-the-power-gone base. Small, cramped, and extremely dark. Adds a few new textures for interest. The first map was easy enough, except you're not supposed to kill most of the monsters.
The second is better, but harder; extremely low on ammunition, you pretty much have to find the secrets (one annoyed me because you have to walk into the right side of a teleporter and it's pretty much up to luck if you find it; guess which side I walked into?) However, nicely interconnected, and there's plenty of windows to cut down on disjointness.
So, a challenge. Not bad - even pretty good - if you can stand the dark and the low ammunition, but I doubt I'll play it again.
Tips: Use the chainsaw as much as you can - indeed, don't repeat my mistake and go for the super shotgun secret until you have the chainsaw, otherwise you'll use up all your shells and be pretty much screwed for later - and watch for the hellknight trap, it's nasty.