I feel I have to update my original impressions. The first hour or so, I'd only completed the first two worlds, and played trials a few times. Now I've completed the third world, and started the fourth world, I feel the need to clarify one point.
This game fucking ROCKS! The levels quickly become interesting, and the graphics really took a step up on the fourth world with some seriously gorgeous background art. The big improvement has been with copy abilities... it starts to actually make sense in the third world. Now my main fear is that the game will be over too quickly, but there is a lot of extra work to collect all the medals, I think.