The only original Zelda on GBA was sadly overlooked. Developed by Capcom (the guy behind MegaMan was the producer), this was one of the better 2D Zelda games.
The main gimmick in the game was Link's ability to shrink. Making Link less powerful seems pointless, but it was a cool.
The quest and dungeons were also top-notch. Though it's far from the best Zelda, it deserves much more cred than Phantom Hourglass.