I believe I was grinning for the entirety of Portal 2, but it wasn’t the gameplay keeping me smiling stupidly. Although fantastic in their own right, the puzzles and gameplay took a backseat to the writing and characterization. The wit and humor in Portal 2’s dialogue kept me eagerly awaiting every interaction. With that said, there were new elements introduced to the puzzles some time into the campaign which added fresh twists while breaking up the testing chambers. Like the first Portal, the game is largely made up of testing chambers which you must use your handy Portal gun (makes a two-way teleport) to traverse while solving puzzles. The goal is to escape the testing facility and the tests are part of an enjoyable overarching narrative.
Although there were new elements in Portal 2, the puzzles did feel a bit easier than the previous game, especially the momentum-based puzzles (you keep your momentum when traveling through portals). I believe this is a side-effect of making the game multi-platform since it needed to be gamepad friendly. On the flip-side of the puzzles being a bit easier than the original games, I found the puzzles in Portal 2 were actually more fun. The added gels in later tests were especially fun to play around with, and I sometimes found myself fooling around rather than focusing on the task at hand.
Portal 2 also introduces cooperative testing so you can play through some really imaginative puzzles with friends or other players online. Portal 2 would have been a great game just based on the adventure-puzzle aspect, but due the witty dialogue, hilarious voice-acting, and just all around fantastic writing, it has risen to one of my absolute favorite games of all time. Easily one of the best gaming experiences I have had in quite a while.