I can understand that this game has a 3+ certificate due to the nature of the game (it contains no swearing, violence, etc etc). It is a game for kids.
BUT don't make the mistake we did, we assumed that the 3+ rating meant that a child of 3 or older could play the game without any problem.
However this isn't the case. My 5 (nearly 6) y.o. was given this game as a present for Christmas, but he can't read all the instructions that come on screen. If we'd known that this would effect the game play quite so much, he might have been bought a different game, that was more fun for him to play.
Having said that, the game is easy to play, just remember that you'll probably have to help explain a lot of what is being asked, and what the various tasks that need to be solved are about.