Listen, Mega 2 is the first and only person I've heard of strongly disliking Yoshi's Island. Its a personal favorite of mine, and I'm sure there're others on the board who love the game.
If you're unsure about it (or any game) the best way to find out if its worth buying is just to rent it.
Personally, I strongly recomend the game, the play mechanics are fun and original, the characters are cool, and the story line explains some of the goings-on in the Super Mario universe.
I'd check it out if you're not sure.
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"Mama mia!"
=ßïllý ¢hîll¥=