I played through Portal 2 nights ago for the first time.

The thing that I love most is that the entire game took me less than 4 hours.

As for the game play it's self, I love portal the way I love a Turn Based Strategy game much more than an Real Time Strategy game... I can take my time, evaluate the situation and then make my move.

I can't remember ever seeing this type of game play in an FPS, so it's a welcome change.