I was on vacation when Portal (and the rest of The Orange Box) was released, so I barely picked it up on Sunday. Adam says it best when he writes:

And the caring about quality - that's what I yearn for. I want to experience things that were designed well. That you pick up or experience and feel that the creators cared and were brilliant.

Portal the idea was pretty good, but Portal's execution was what made it one of my favorite games ever. Not too long, not too short, with enough surprises, humor, and balance to make it a truly perfect game.