Basically, the game boils down to three moves:
Jumping into a portal to jump high, jumping into a portal to jump forward, and forcing an orb into a portal.
The game was ridiculously short, and while the humor and other wraparounds were entertaining, they could not hide the lack of depth in the main game. Braid, a game often compared to Portal, was a game I enjoyed MUCH more, because it was possible to LOGICALLY figure out the optimum solutions. In portal, some solutions actually require cheating (Many of the challenges require glitch-exploitation, or pixel perfect shots/timing).
I expected the challenges to really fill out the game, and I must admit, the "least portal" challenges are kindof neat, except when they require ridiculous moves. The other two challenge tpyes, least time and least steps are ludicrous. Least steps is wretched because it counts ALL steps, INCLUDING involuntary ones. A *Step* should be defined as pressing the "W" key long enough to move your character forward. The least time challenge turns the game into a generic twitch game, which goes agaisnt the theme.
So really Portal deserves TWO scores. I will borrow from figure skating and award 9/10 for artistic merit, and 6/10 for technicality. That works out to a 7.5/10, which sounds perfect.
Flame away, but you know, as always, that I am right.