We're going to have fun, with science! This was by far my favorite single player game of the 2011 year. I have not played the first one, but I did some research on it and I understood enought to understand Portal 2. I was looking at reviews of this game in Game Informer magazine and one of the interviewers asked the producer of the game about the ideas they had for Portal 3. The producer replied with a simple "Oh so you are trying to get me to spill secrets about our up comming plans." This was enough to get me hoping for maybe a Portal 3 comming out sometime this year, but I cant be certain. Lets wait and see! Portal 2 featured a new online 2 player co-op mode that allowed you to play as two robots. P-Body and Atlas. The co-op mode was probably my favorite feature because it was fun to solve puzzles with your friend by your side. :P
Brilliant! Love the game, absolutely love it. But my internet connection's been so bad that I've only been playing offline, meaning no co-op as I have no friends around to co-op with... but it's still fun!