The portals are a lot of fun to play around with. One of the first things I did was shoot two portals above and below each other and fell through them really fast like I used to in the Portal games. I like how the game ramps up in speed after awhile, and the levels are designed pretty well. The bugs are pretty rare and unimpactful, and sometimes even a little funny. They're quick fixes so they don't really take from the enjoyment of the game.