A replacement episode 1 for Doom. Nicely done.
Map layouts are all right. There are some good individual areas but the larger, later maps end up with a bit too much of the all-too-common disjoint rooms-and-halls syndrome.
Texturing is fine. I didn't really notice any particularly bad misalignments, or anything. In fact all I can really remember of bad texturing was in E1M5 where the poison signs around the big slime pit at the start are repeated too much, too close together.
It has some common themes. It likes monsters in cages on the walls, and spectres in deep slime pits (somewhat unfortunately in the latter case, as they can be hard to shoot.) It doesn't stick completely to E1 stuff. It uses a fair few E2 base textures, and there are berserk boxes, although no plasma weapons. (There is a rocket launcher, but emphasis on singular. See below.) It is also rather full of fast doors. These didn't exist in Doom until Doom 2 came out. However, I'm not sure if I'm noticing them so much only because the /newstuff reviewer happened to mention them.
There are a few little bugs here and there. One door on E1M3 doesn't open because it uses switch-type linedefs instead of manual ones (the usual fake manuals ZDoomism.) Another door in E1M7 has on one side a repeatable walk trigger to open it - I think it's meant to be a switch trigger(!) Fortunately the door starts off open, but closes after you go through it and you can't re-open it. It doesn't break the level though.
Difficulty is low. I did 100% runs of most maps easily from a pistol start on the first attempt. This is not unwelcome in this modern age of maps that seem to be, not just hard, but obnoxiously mean-spirited and as annoying as possible.
The text file notes "Each level is doable from a pistol start although it is recommended that you play it through as a whole episode". This is no idle remark. As I mentioned, the maps are easily doable from a pistol start. But the only way you're going to get the rocket launcher is by doing the whole thing and visiting the secret level. This is obviously deliberate and I found it quite a nice touch.
In summary this is a decent, old school (old school enough that it even has a story line in the text file!) E1 replacement. It won't set the world on fire but it's certainly fun enough to play and replay a few times.