Seven maps with oldschool-ish texturing, decent layouts, a lot of monsters, and a paucity of ammunition.
The whole wad is a mix of old and new. It seems to deliberately take the style of mid-to-late nineties maps, especially deathmatch maps. Replacement sounds (the teleporter from Quake and the player death from Dwango5 are here), hidden credit picture of the author, and so forth. (That said, see the final paragraph - this wad was a deathmatch wad in its past.)
The first six maps are small bases, buildings, outdoor parts with grass and vines, a few excessively dark areas, that sort of thing. The final map is a remake of Underhalls (Doom2 MAP02) in the style of Plutonia 32 (i.e. crowds of high-tier monsters). It was probably my favourite of the set. It's certainly the only one that doesn't suffer from a lack of ammunition: in the wad's text file, the author writes he "put a lot of calculation into these regarding ammo and health balance", the result of which seems to be that, on the early maps at least, you must make every bullet count, and are allowed to take very little damage. I don't care for this type of gameplay, but I guess other people do, there are a fair few wads of this nature.
There are a few bugs. Several unreachable secrets, both of the all-too-common "thin sector before a step up" type, and the rarer and more interesting "special cleared by floor transfer". An example of the latter: on map01, the super shotgun is on a crate next to your start position, but when the crate lowers, it loses its secret property, so you don't get credit when you go back to collect it. These were far more common in nineties wads before the line special behaviour was well-understood, but it's surprising to see it in a modern wad. There are also a few unkillable monsters (a pillar on map06 full of revenants does not lower) and some visual glitches of the "map was tested in OpenGL mode" variety (watch the BFG lower out of the ceiling on map04)
The whole thing is given an otherworldly atmosphere by the addition of a palette that smokily tints shades of dark grey with blue. I'm not really a fan of replacement palettes. On the other hand, the deep blue sky texture is very nice.
Finally, upon loading this immediately gave me a sense of deja vu. It turns out this tdevil2 is partly based on a deathmatch release named Zmatch 2013 which I experienced at a couple of Odamex events last year. The first three maps are from here, somewhat modified (not just with monsters added, there are structural modifications too), as is the palette and sky. Curiously, tdevil2's text file does not appear to mention its ancestor.