This is a really fun and great map, good environment design and tricky puzzles. The behind-the-scenes areas had great mood. There are a couple of dodgy parts: For example the box-climbing room reminded me of similar levels in the original "Doom", and I'm not sure that's a good thing. Portal is a puzzle game, not a platformer.

Additionally, being able to break glass with objects is not always obvious and can take time to figure out, especially as there are also unbreakable glass walls in the game.
The level design is worth a praise, but the map suffers from the same disease plaguing most user-made maps out there (not limited to Portal): Lighted Rooms With No Lighting Fixtures. As a student of architecture I'm very interested in the believability and style of the level design, and the rooms and hallways with no lighting fixtures but still illuminated (with magic?) always catch my eye, although in this case these scenes are fewer than most maps.
Another annoying thing to me is illogical and confusing level design. In real world nobody would build a research facility consisting of corridors and rooms after another, it would be very frustrating for the guy working at the last room to walk 12 kilometers to his desk every morning.

But this doesn't apply as much to Portal, as the test chambers are designed solely for portal puzzles and need no logic. Overall this is a very, very good map.
Huge success.