Fun game, great to play with your kids and it's very, very easy.
Why I loved this game: just the fact that I could play this with my son, which at the time didn't play much video games, was great. He loved this game and still plays it sometimes even thought we finished it. It has a lot of charm, controls perfectly, it has a really good storyline for kids and I found it to be very creative. One of the best things about this game is when you transform to an object and both players are now a part of the same character and each has a different thing to control this character.
OK, let's talk about it's main fault: it's very easy!!! You don't die (don't think so, don't know how, it never happened). Other than that, they do have some stages that are challenging to achieve (I remember having a hard time when Kirby transformed to a train, and you put train tracks using your Wiimote, not easy).
I rate this game 8.5 out of 10. If it was more challenging, I'd easily give it a 9. A must buy for any 4 to 7 year old who has a Wii (don't rent it, buy it, especially since this game has a dramatic price drop now). I remember EBgames in Canada (same as gamestop in U.S.) was selling it for 2.99$ used, or 4.99$ new!!!
If you need to buy a gift for a kid, and he has a Wii and doesn't have this game, it's an ABSOLUTE no brainer buy!!!