Geometry is nice (as usual), very detailed, but there is some little problem:
A step is broken; there is a very cubic sandy part on a side and it makes a really strange doorway. Also, the platform at the midle of the map doesn't connect with the sandy part. It's OK for the eyes, but it makes a gap in which you can fall. That's not good for the gameplay, you may fix that with clip.

I feel that the lightning doesn't really exploit shadows (nor shaders), and that it is not enought funky for my taste, but that's not a complaint :P. I like your style/way of mapping, really different than mine.

It certainly looks nice.

Hey! You stole my falling sand idea! :P
Heh, just kidding. Even if you did, I don't care.

An interesting map, it definitely shares some similarity with may map, in particular the sand & metal feel, though your sandy areas have more erosion.
The texturing is a little too crazy for my tastes; it looks like you used most of the textures from Lunaran's textureset. You could especially tone down the use of glowmapped textures--there are way too many point light sources. (Not the light entities themselves, just the textures.) You could also consider using strip lighting, which is somewhat easier on the eyes.
I'd also suggest hollowing out the falling sand column so that if you go through it, it seems like you're actually in it.
Oh, and one little slip I noticed: if you look at the sandy area under the yellow armor, it isn't clipped. One can easily get stuck on the metal bits.

Overall, architecturally nice, but doesn't appear especially playable.

I like this map and can only agrre to what Kaomé and SheeEttin said.
Maybe Kaomé meant the same as I do about there being a gap between a sandy-tunnel-entrance and the platform/walkway .. although I did not "fall" into it, I get stuck there - use clip for player movement comfort I'd say too!
That is a part where I felt jagged out of the otherwise well detailed and themed geometry you've made - the tunnel entrance has very obvious "basic cubes" (90° corners leap into the eye there), but other parts could use just a tiny bit of sprucing up to come up to par with the rest of the map - at least IMHO - but the general look-n-feel is really quite high, so it's no biggie, just a "wouldn't it be perfect"? :-)

The bits I'm dissapointed with are the missing "mapmsg" and that you packaged the map into folders called "Packages/Base" as opposed to the correct lowercase "packages/base" which is just a head-shaking nuisance - fix that up and you'll get 4 stars easy - maybe 5 if I test-play it some more and find the layout extremely suitable .. on my previous run-through I wasn't instantly convinced it would provide "remarkable" gameplay .. 5 stars is just for the absolute outstanding maps in my book .. 4 stars is already release worthy .. 3 star maps have nothing wrong, just nothing spectacular either and you can guess where it goes from there.
I'll keep you on 3 stars until you've at least fixed the packaging issue.