I was gonna classify it as an instant classic as it reminded me of The Lost Vikings but this game has it all.
I got sick of playing recent games so I decided to give Trine a chance! I found it was a good old school fun and exciting game like I haven't played for a long, long time.
The graphics are excellent without being too demanding(1920x1080 maxed w/o AA&AF). It sounds incredibly good although the dialogues aren't always inspired, but hey it's a game for kids. It is challenging without being too hard and it ain't very short either. All in all a good play that reminds me how the old games were made.
Despite the few bugs encountered(I suggest you update the game once you get it to v1.04 or newer) I had no problems with it. I even played some levels more than once to get more xp and secrets. Re-playability is small as you won't get to play the game more than once.
+great atmosphere music and exciting story
+not hardware demanding
+multiple options to puzzles and good old school fun
-price a bit high