Pros:

Unique setting
Well made in terms of using text hints, hordes at specific times etc., it's not JUST a map.
Unique progression, not just "kill zombies move forward."
The ending reminds me of Zardoz.

Cons:

The 'weapon caches' were not obvious for first timers.
Progressing through might be too confusing for impatient players.

Conclusion:

This is a super-cool map, I love the design.  It's tremendously creative and I wish I had come up with something as neat as this.  The space skybox looks really good - I really get the sensation of a vast endless universe - and there are plenty of opportunities to see it. Love the flying saucers at the opening and ending.  Best of all, this map is just plain weird - a combination of a strange space station, Mayans, and as I said above, a Zardoz-esque head at the finale.  All in all, LOTS OF FUN!