Super Mario World is timeless classic.
The Bad: Nothing bad about it
Super Mario World is without a doubt the best video game I have ever played. At the end of each world, there is a boss castle, you go through a series of traps, until you get to a red door. Then, you fight a koopa, and when you beat it, you unlock a different color Yoshi. Each yoshi has a special ability, when you swallow a shell, then the Yoshi's ability activates.
Example: The Blue Yoshi's ability is he can fly.
There is no doubt about it that this is the best Game Boy Advance game out there.