Good style and details (also on the ceilings!). Indeed, very well done for a first release.
I agree the colored lighting is a bit heavy in some areas, it can easily suck out contrast, but by and large it's okay.
Played on hard and it was a good challenge overall, except for getting stuck on details in the arena parts. Felt like I was low on health most of the time, but managed somehow - could have used that one health pack that fell out of the level...
Bit hell-knighty perhaps. Would have wished for an explosive weapon earlier, though maybe there is one in a secret I missed, and possibly a few more cells for the end fight.
As you may have noticed, the map exceeds the standard models limit by 12 or so. Could have been easily fixed to work on the vanilla protocol. Just FYI for next time; there are always some tricks one can employ in this regard.
Since someone complained about the packaging, I might as well comment on it, too: would be nice if you could repack the release without the folder, so that the zip contains only the three files in its root. This way, it could be used with the Quake Injector on Quaddicted.
Good job; hope to see more from you! Demo