Improves on the first and surpasses even the greatest of expectations.
The storyline picks up right where Portal 1 left off. If you have played the updated version of the first, you'll know that you were dragged back into Aperture after defeating GLaDOS. You wake up in a new style of containment chamber, and work your way back to GLaDOS's chamber with the help of a personality sphere named Wheatley. This little guy is absolutely hilarious, and will keep you company throughout the game. It felt different having somebody on your side, but it was a fun experience. I won't say much more about the storyline, but you do get to meet up with GLaDOS as well as hear messages from a Mr. Cave Johnson, who is also incredibly humorous. This game is all but guaranteed to make you laugh hard and on many occasions. That's not to say it is all about laughs, the storyline really does make you want to advance through the chambers, whether it is Wheatley egging you on, Cave Johnson talking about Aperture Science, or GLaDOS making you want to kill her again.
The game can be broken up into roughly three sections: Destroyed Aperture, New Aperture, and Old Aperture. Destroyed is the first Aperture that is seen. There is a lot of rust on the walls, and the chambers look like they are hardly functioning. New Aperture is what it looks like after GLaDOS cleans up the place. It is similar to the first Portal, but the improved Source engine makes the game look much more vivid. Old Aperture is what Aperture looked like in the mid to late 1900's. You can see where GLaDOS got her inspiration and it is fun to learn a bit about what Aperture was like before GLaDOS took it over.
Co-op runs through the environments in much the same way that the single player does, introducing new elements relatively slowly so both players can get used to the new game mechanics. Whether you are a new player playing with an experienced, a new player playing with another new player, or two experienced players playing together, you are bound to have fun playing together.
With free DLC around the corner, Portal 2 will be even longer. I do admit, even though it was much longer than the first game, it was a bit short. This, and the fact that the game was a bit on the easy end are my only complaints, which will both be addressed in the DLC pack.
So, let's just break it down pretty quickly.
Gameplay: 10 - New game mechanics improve on an already amazing game, and ensures there is something for everyone to enjoy.
Graphics: 10 - There are different environments to take in and admire. With the improved Source engine, the game looks incredible.
Sound: 10 - The soundtrack is again amazing, as are the sounds physical objects make. It creates a real world, and an immersive experience.
Story: 10 - I've never laughed at a video game as much as I did at this, but I've also never been engrossed in a video game as much as I did with this.
Final thoughts: Get this game. It is up there, if not the best game I've ever played. It is exciting, funny, and just plain fun.