I played two more maps today:
The gameplay in this map is hindered by the massive, open spaces at the beginning. You fight a lot of Revenants here, but the only thing challenging about it is the lack of walls to block their homing missiles unless you head into another area and risk triggering more monsters. Revenants are not fun to face in open areas.
Also it's fairly predictable. If someone doesn't guess that all those raised platforms running along the outer walls are going to suddenly become occupied by Mancs and Arachnos, they haven't played any Doom map ever. The symmetrical monster deployment, which is IMO a common failing in Doom maps past and present, means you regularly have to re-fight the same battles, none of which engaged or challenged me.
The final battle in the arena is much more interesting. It's yet another mass battle against Revenants and Hell Knights, but it is different from the same types of fight present in nearly all other SF2011 and SF2012 maps because of its scale and the way the HKs are deplyed in a series of stepped platforms. The sheer amount of incoming Hell Knight fire is impressive and partly negates the player's need to fight back, since the Revenants in the middle are being constantly bombarded.
If there is a BFG in the map I missed it or skipped past it. This means tiring and repetitive slogs with the plasma rifle, rocket launcher and super shotty.
With great respect to the author, this was one of my least favourite SF2012 maps as I found it dull and uninspiring.
I simply cannot survive the starting room on UV. More playtesting is required, but I would rate its difficulty level as obnoxious rather than challenging. The number of monsters surpasses army level and effectively becomes a brown cloud of fireball-spitting death. Getting only a couple of shots out of the BFG is too harsh for me and I'd have liked more health bonuses. Getting more plasma means you activate dozens more Revenants. Surviving the massive battle at the start means you get to make progress.
I skipped down to the easiest difficulty level, something I have only ever done out of curiosity, and was surprised to receive double ammo. I would count this as essential; it's nowhere near as challenging as on UV, so thank you for implementing difficulty levels, but I was regularly running back for more ammo. I can't see how there would be a decent balance on UV where there is effectively half the ammo and 30% more monsters.
After battling for a quarter of an hour I was starting to get fatigued and the low difficulty level, while still tough, was irking me. I checked the automap and realised I'd discovered only about 10-15% of the entire map. A couple of IDDTs later and I had to call my brother to show him how immense the map was.
This map was very attractive with the metal-and-lava theme but not the hellish theme I would expect for a final map. While I thank the author sincerely for not making this an IoS map, there was honestly far too much time and effort put into this level and I cannot imagine wanting to sit down for 2 hours and play through it all.
Like Twobox, I regard this map to be defeated by its own size. Anathema was utterly superior to Twobox in the gameplay department, even if it was far too hard on UV, but both maps are not ones I particularly want to play again. That said, I do look forward to watching a playthrough on UV - I will probably be skipping through it though since it's probably going to be 30-40 minutes long, even for a speedrunner.