Really impressive in scale, and remains engaging throughout - even when one would think the spiral ramps would get repetitive, there's something about this map that makes progress so satisfying. It is suitably generous with weapons, which I find really important for making this sort of thing work.
I found 18/21 secrets. Some were interesting, but there was a great deal of ramp jumps, drop-downs, and illusionary walls. The rewards were usually extremely satisfying regardless, especially the secret fights on the additional islands, which play more like traditional Quake dungeons than the main one.
This might not be for everyone - I generally prefer small maps to this kind of indulgence, although I did enjoy it a lot as I've suggested - but it is the perfect and final encapsulation of the specific otherworldly awe that Koohoo alone can evoke.