First thing I noticed was that this game has very beautiful graphics. It is a 2D platformer, but it looks so dynamic and magical. I enjoyed a big part of the game almost only because of the graphics. It enhanced it, let's put it that way.
The gameplay is good as well. There is some action and you have to solve some puzzles to get further in the level. The combat is simple, and not overwhelming. Some puzzles are simple, others are quite difficult to solve. The co-op mode is good as well. You play basicly the same levels, but now with two characters. I doesn't make it easier at some points, because you really need to help each other. So it makes it really interactive.
The story is nice as well. The characters are good, they are well involved in the story, not just observing people who don't interact at all.
Really, I don't have anything negative to tell about Trine 2. I just love this game, it is fun to solo, and fun to play with a friend. I would recommend it to everyone. It is on sale quite often, so you can save a lot of money on that.
My rating for this game: 8/10