What I liked:
-very nice graphics, very polished, immersive
-game is not too punishing (though you have to come back sometimes to a previous checkpoint)
What I didn't like:
-could have used more boss fights and more varied bosses too
-could have been a little bit longer - but I guess that its length was also setting the basis for its price
All in all I am hardly waiting to get Trine 2, which should be an improvement on Trine (for what I've read at least for the bosses part). Trine was for me a game for which you can't wait to get home to play.