You might want to check that a third of your chamber can't be skipped before calling it "advanced". Two of the laser cubes in the first room aren't needed and players are likely to take them into the next room (it's a technique taught in the original portal game and reinforced in portal 2). If they do take the cubes with them, the third room with all the timed buttons becomes redundant as the player has three cubes to play with already.

I've got a little collection of chambers going and I'm always interested in feedback on each chamber or the collection as a whole. I'd be grateful if you'd have a look:
Elementary