Yoshi's Island was originally released as Super Mario World 2 on the SNES, and continues Nintendo's plan to rerelease the best of the SNES.
Don't complain just yet though, because Yoshi's Island is a masterpiece. Maybe the greatest 16bit platformer, this game will make you smile from start to finish.
GBA enhancements are as thin on the ground as in other Mario Advance releases, and the game doesn't really reward you for bothring to complete the game with all stars, but those are minor quibbles.
This is a true classic.