Portal 2 brings back what you loved of the first, and introduces new things to the recipe.
Story: Quite simple, but very likeable. You are Chell from the first, and you are set on escaping Aperture Laboratories. There is a dynamic cast of characters (Three to be exact.) Although there are very little characters, Valve makes them intriguing and exciting. The characters consist of GLaDOS, the insane A.I who just loves to test, Wheatley, the hilarious British robot, who will accompany you on your walks and Cave Johnson, the big-shot who runs the entire facility. GLaDOS is dry, and sometimes she says some very dark stuff. Wheatley, voiced by Stephen Merchant, is just plain hilarious, and every line he delivers just will crack you up. His accent really adds to the humor. Cave Johnson is introduced later, and he says some humorous lines as well.
The story itself takes twists and turns, and has some back story, if you find some secrets, which actually connects to the Half-Life universe. The ending itself is amazing, and it truly feels like Valve have worked their hardest to create a perfect game, set with game play, story and overall sheer awesomeness. 10/10
Game Play: There are two modes to Portal 2, single and co-op. Single takes the role of Chell, while Co-op is the adventure of two quirky robots. Single player has somewhat different puzzles from co-op, which requires you to think in many ways possible, using Repulsion Gel, Aerial Faith Plates and more. Valve decided to spruce up the variety a bit, so they introduced new mechanics that will get you thinking. I am glad that they did this, for the first Portal suffered from having not as much variety, which resulted in it being shorter. They have seriously improved the formula, without ruining the good parts of the first. So anyway, the puzzles are sometimes tricky, but not over the top frustrating, so you can satisfyingly complete a puzzle, without smashing your T.V/computer. You need to think with gravity, change your perspective of what is going on, or ask yourself, "What will happen if I do this?" You also get talked to by the main characters, so in-between puzzles you can get amused.
Co-Op is a fine addition to this sequel, which was a very smart move by Valve. You play two robots, and will have to co-operate with your friend to get to the end. GLaDOS is still there and likes to commentate on your winning, and more often failures. Co-op is not easy at times, and you will need to discuss your situation with your partner to prevail. The puzzles in co-op require four portals, which actually divides single player from co-op. They need different tactics. You can also hug, dance, do kung-fu and other actions, which portrays the game's light-hearted nature. I think that the game play is intelligent, and is very improved. I forgot to mention that Valve will be releasing free-DLC to quench your thirst for testing. 9/10
Graphics: Valve was never known for amazing graphics. Considering this still uses the Source engine from a decade ago, it is pretty incredible. Everything is done well. Now that Aperture has been penetrated by plants, and rust is littering the once squeaky clean floors, Valve has had to put quite a bit of detail into the surroundings. Not that this entirely matters, for you will be either too stumped or just laughing at jokes to notice this. They have put definitely effort into graphics. 8/10
Replay Ability: Portal 2 kind of falls short here. After the two very fun campaigns, you can look for secrets, hear the dialogue or just wait for the DLC. It's very fun, but a lot of puzzle games are done, when finished. The reason I am not marking this down that much, is because of the free DLC. Thank you Valve! 7/10
Overall, Portal 2 is an excellent package. I have completed Single Player, and was actually amazed at the ending. Co-op is fun too, but only with someone willing to help. Level design is great, characters are hilarious (especially Wheatley) and Valve proves that they can create masterpieces in the videogame industry. 9/10