Very interesting release, and not just because standalone id1 maps are rare nowadays.
The first noticeable thing is how the map chooses to use simple (but striking) shapes for the architecture, and then applies highly detailed textures onto those shapes. It's a clever extrapolation of what id was doing with the same textures in 1996, just on a different scale - and something of an antithesis to the detail-by-complex-brushwork style. (Which was so prevalent this decade, going back to Rubicon 2, and possibly Ruined Nation before that.)
The texture combinations were interesting too, as there was a lot more to them than just idbase + Rubicon. (Don't think the RRP toxic box signage escaped my eye.) In most cases it was 90% idbase and 10% other stuff, which lent itself to giving the map a "Quake+" vibe.
I liked that there was some considerable variety in each major encounter, with the usual order of things being a little tilted - it's not often you see a horde of Grunts after
battling multiple Ogres and Fiends.
I wasn't sold on the flooded Zombie basement myself, mainly because of the liquid impeding my movement against the Voreballs. Mapping protip: you can get away with controversial encounters like that simply by placing a megahealth beforehand. ;-)
Here's a double skill 2 demo
with outstandingly lazy play and multiple lapses of judgment (sorry). I enjoyed the map a lot regardless.