Damn, this is what New Super Mario Bros should have been.
The graphics are just cutsie enough to be good looking though the look of the game is not mind bending. The bright, colorful backgrounds and great animation make this platformer stand out. Everything is just so pleasant to look at. The sound is full of bep-bops that fill the happy tone of the game rather well.
The gameplay itself is top notch. The controls are superb, the levels are gynormous, the bosses are awsome, and hasn't everyone wanted to be a baby Wario? The level of challange is brilliant too. The levels get harder and harder to do as the level progresses and the final boss is appropriatly tough. But really stands out is the replay value. This game is mean about collecting things. You HAVE to collect EVERYTHING!!! to get the better ending. Its a fun chore, that challenges ones sanity. Thus the game strikes a balance for the new-comers and the hard core.
If you played New Super Mario Bros, and came away slightly disappointed with its difficulty, try Yoshi Island DS. Heck if you own a DS, this should be in your library. Happy Egging!!!