It's like people whining about the Materia system in FFVII, when that's just the Job system in a new light.
Also, I've owned Yoshi's Island DS twice. Both times it was a gift. And it sucked both times. I mean, crappy music, not as awesome graphics, horrible level design, stupid mini games, and only 5 worlds?!? What a waste of time.
The only slightly cool thing about it is if you look at the fact that Artoon helped make it, and unless I'm mistaken that was founded by Yuji Naka or something, so the whole SONIC CREATOR MAKES MARIO GAME aspect is cool, but not really. The shitty quality of the game kinda destroys anything that fact might have had going for it.