well, finally I beat the game yesterday. I took 12 hours which I guess normal. not too faster, too slower. overall, it is really a good puzzle game. I love it. (well, every game is the same as you experience when you play it first time because you are not familiar with the whole environment or trick whatever) only thing is that I seemed to use my brain way too much. I got a headache twice before finishing it. it never happened when I played other. damn, Valve. I need a compensation of my brain damage!
the whole puzzle is very innovative, fun. story is very interesting even though there is no cake anymore. but in the end, entire turrets say 'goodbye' in end of game. they sing. adorable? when I ended up with cornfield, I was wondering what portal 3 will be. I don't think that we will see GLaDos anymore in portal 3 if Valve will make. I thought that GlaDos was human killing AI in first game. but in this sequel, she was kind of little friendly since I rescued her. then we made a friendship (?).