Jr. is just a port of the original Monkey Ball, only with worse graphics, bad controls, and overall poor execution.

User Rating: 4.8 | Super Monkey Ball Jr. GBA
Gameplay: The gameplay is just the kind we've come to know from SMB, but the GBA pad obviously ruins the gameplay to a poor extent. Up, down, left, right. The only direction you can go without going too far and falling off the stage, and sometimes, not even those listed above will help you.

Graphics: Poor. Very poor. The graphics are very blocky, and you can't even see your monkey's face. Animations are crude and rough, not to mention slow.

Sound: All the sounds are there, reduced to portable fashion. Reduced, pretty badly.

Overall, this isn't really a game. It's just a broken port. Anyone looking for a good portable SMB experience should pick up Touch and Roll. But if you only have a GBA or SP, and you are NEVER getting a DS in your life, then, and only then should you pick it up. Otherwise, a bargain bin find.