Feels shorter than what it is.

It is decent. The rooms are pretty neat for its time, no big errors, except that there isn't enough ammo to kill the enemies in the first half (for the second half there is more than enough), but nothing spectacular also.

Very nice. I really enjoyed the architecture of the thing. Beautiful moment in the Shubby start area trying to dodge Scrag fire with Ogre grenades coming from a vast distance in an uneven corridor; a very cool lava fissure in the main chamber (as pictured on the poster); the broken coffin is fantastically foreboding and the associated mechanics are an absolute joy.

The map is inventive and distinct in particulars while aping classic id1 mannerisms judiciously: the exceptions are the door access gauntlet, which felt a bit loveless & procedural; and the exit encounter, which felt rushed and haphazard (significantly, increasing difficulty from normal to nightmare had no effect on the final encounter, which feels anticlimactic and undermining of the overall experience as a result).

Short, sweet and clever enough to incentivise replay at higher difficulties: the main arena battle does get marginally more challenging, but once you find the trick, it's no significantly different an experience at nightmare. In fact the only significant challenge on nightmare is the opening area; that could stand to be tweaked.