Ok, I only really had a short run through the map so this is by no means thorough. A lot of stuff has been mentioned before too, eg the absolute greyness of it.
I was actually surprised to see you've used a couple of sounds in the map. Unfortunately there isn't any wind at all in space, but I doubt anyone really cares. The sound you've used for the rocket boosters (which are a nice touch may I add) is questionable to say the least. I can't really think of anything to compare it to, except 50 ugly children tapdancing really fast in an almost soundproof room. Not that I'd know what children in a nearly soundproof room sound like...
The sky you used is extremely bland, it's a black canvas with a clutter of white "stars" on it. I've never been very far up in space myself, but you can probably see the sun from up there. You might want to consider raising the level of the sky a bit too, gauss jumping to the top can be a pain sometimes.
Here are a few screens I took of errors I found.

1. Three errors in this screenshot. If you construct the brushes the way I've outlined, that texture error will be eliminated. There's a small gap in the fade where the yellow circle is. The red circle is the worst error of all, but still easily fixed. Read this tutorial about r_speeds and face splitting.
http://www.snarkpit.com/editing.php?page=tutorials&id=60&highlight=splitting

2. The intricate drawing in the top left clearly illustrates the need for an improved sky. The green circle surrounds a rebellious brush which is mysteriously lower than his friends.

3. More face splitting here, refer to screen one.

4. There is a hole in the underside of the stairs here. The undersides of all these steps would look much nicer if it was all one smooth slope rather than inverted steps. A slope would help the r_speeds too.
Overall it's quite a clean architecturally sound map, nice work. I'd suggest experimenting a bit more and being more creative. I'll be looking forward to your next release. :smile: