IGN- Portal 2 Review

IGN says: Portal 2 makes the original look like the prototype it was. It's filled with a larger cast of characters vividly brought to life through brilliant writing and some of the best voice acting in video games. Its puzzles are challenging without being unreasonable, and, once you're finished with the single-player mode, one of the best co-operative experiences on the market awaits. Valve cuts no corners and finds ways to make you care about everything from the major characters to the cubes used to solve puzzles. From the beginning of the single-player story to the end of the co-op mode, Portal 2 is a novel, unforgettable experience.