First off, as mentioned by others, yes its whole presentation is very childish (though presented excellantly) - you have to look past that, and enjoy a game that underneath its looks is superb and fiendish adventure / puzzler.
Its essentially a point and click game (using the wiimote), with each level being one big puzzle to try and get to the treasure chest that is showed to you at the outset. What makes this game so great, is the fact it utilises the wiimote better than any other game on the Wii, integrating its use fully in the puzzle solving of each level.
Not only that but the levels / puzzles themselves are so well thought out, with logical thinking being required 90% of the time to reach the goal. Though one small gripe is that the other 10% of the time is trial and error, which i have found to detract slightly from the overall experiance.
However, overall, if you love adventure games with fiendish puzzles, coupled with the best execution of the Wiimote - you wont be disappointed.