Be sure to include that .def in the pk4 if you release it with a GA. It's a bad idea to leave the vanilla game out of the equation...
I think the layout is pretty fun, and I like all the cool trick jumps and movement possibilities--I just ran around it for quite a while by myself playing with routes and movement. Good job on that!
There is still a lot of work to do on lighting, and even more work on texturing, IMO.
The lighting seems really oversaturated in a lot of places, and I'm not digging the reddish everything vibe all that much (and even less when it's broken up by, say, bright green

). I really think the level would look better if you toned down the colored light a lot. There are also a few places where I'd consider turning shadows off, like the lights at MH and YA. I also notice a lot of places where there's a light that's quite bright without any actual light fixture or light texture anywhere to show where the light is coming from...
Texturing is kind of all over the place--there are a few places where it looks nice, but a ton of spots where textures are just cut off in the middle without any sort of edging or cleanness to it. You also have textures scaled up hugely in a few spots, which looks weird to me (for example, under RL, both the metal texture and the grate around it--I'd scale those down and use different textures). Get used to using the "fit" on the surface inspector.
Finally, I think you could tweak a bit more performance from this map with some more portal work, although it's not horrible right now. There are places where I think they could be improved, and they are also sunk into geometry in a few spots--this shouldn't be necessary...?
For the bloodpool itself, it seems odd to run through it and still get solid footstep sounds. Maybe make the blood really shallow and make a custom material with flesh material type for the floor, and you would at least get that squishy sound? Dunno...
Cool layout and fun to run around in.
