Story: The story of Portal 2 begins in a room where you do some "calibration".You are in the shoes of Chell, as you were in the original Portal. You really just do some looking around the room to get used to the controls. The comedy of Portal 2 also starts off right from the beginning. I really do not want to spoil too much of the story so I am sorry about how short this is going to be. You help out a robot named Wheatley. You end up turning on GLaDOS with the "help" of Wheatley. Portal 2 brings laughs and laughs, and I recommend playing this game twice to catch things you may have missed. The Co-op version is pretty fun, and I recommend playing this version whenever you have friend that is competent enough to play as either Atlas or P-body.
Gameplay: The gameplay is much like the original, but with a few new added elements. The Co-op gameplay is pretty fun, but some of the puzzles are really difficult. But back to the single player, the new added elements are "paint". There are multiple kinds of "paint", Blue makes you bounce higher, Orange makes you go faster, and White allows you to put portals in more places. With this new added element from Tag: The Power of Paint, a student made game that Valve got in contact with the makers. I found the game to be extremely fun but difficult at times. One other thing I disliked about it was the loading time, but that was not such a big deal with me (seeing as I have played Gran Turismo 5).
Graphics: The graphics of this game were extremely good, or at least I thought so. I thought the ending scene was probably one of the greatest scenes I have seen come from the PS3. I absolutely thought that the art style was absolutely perfect for the game. One other thing is that the Paint physics were extremely good.
Overall: This game had very few flaws, it may be a short game but I think it deserves a second play-through to see all of the hidden jokes you might have missed the first time. The Graphics were great and Gameplay was as well.
(overall scores are found by finding the average of the other 3)