Just played through this map a couple times, and I'm very impressed. It's solidly crafted, well-planned, and has some very creative puzzles.
There is one small problem: in the huge fling room, with the emancipation grid, if you go up to the wall just below the button and look down, you can see outside the level. Not map-breaking, but if you plan to release an updated version, I can't imagine it being to hard to fix. If you need a better explanation of where it is, just ask.
My only other gripe is the turret ambush near the end. My first time through, I went in, the doors sealed (which was extremely cool, might I say), and then I died in a hail of bullets. In my opinion, there should be some kind of indicator - nothing to obvious, but maybe a single-dot-square where the first turrets show up, and a two-dot-square on the second wave, just to give first-timers more than luck to help them.
All things considered, a great start to Portal mapping - I really enjoyed this map.