Top-notch map - has a few minor problems though.
Aesthetics
Flawless, full of detail; no complaints. (Was everything really made in the contest's timespan?)
Difficulty
Difficulty was just right, growing as we progressed through the map. If you want a label I'd call it medium: goals were clear, but the means to achieve them needed to be discovered and deduced. The third puzzle got me stuck for a while, forcing me to revisit the map and complete it. I've attached a demo of my solution which I think is intended: I certainly didn't walk through laser beams like others have done!
Gameplay
There were a few irritating niggles. In the third puzzle, the #3 and #4 signs are mixed up causing a bit of frustation. Sniping portals through the laser field to turn on recievers #1 and #2 was a fiddley manouvere. I managed to get stuck by the locked exit door too. Walk over to the exit door via a light bridge and then place both portals inside the exit zone, behind the fizzler; you are now stuck.
There was no indication in the final puzzle that the laser target which disabled the light bridge also disabled the fizzler upstairs - that extra bit of clarity would have been useful. An arrow or some kind of indication to reveal the first panel beyond the laser field to extend the light bridge from might be something to consider also.
The Easter Egg buttons should have done something individually - it needed . I only discovered the first one, but I spent a minute or two trying to work out what they did in the puzzle chamber. Ideally they shouldn't look like a test element: perhaps the underground button or throw switch model would have been more appropriate.
On the whole, though, the gameplay is great, keeping you constantly thinking throughout the map. Here were some highlight moments for me:
* Being encouraged to jump into funnels
* The small break sections between each puzzle to prepare for the next challenge
* Pulling off the Double fling using your cube as a coop partner
Bugs and Mapping Details
* The walkway above the offices had some strange physics going on - I jittered and slid about when I stood on it.
* Needs more func_detail - I looked at a few sections of the map with mat_leafvis 3, and pretty much everything appeared to be a world brush.