Great, in one word.
Surprisingly, this is a puzzle game, where you move an iron ball around and destroy exits to get to new stages. There are cabbages to collect, items to find, and enemies to outwit.
Some of the puzzles in this game are very challenging and will take you time. Beating all 8 worlds will take you quite some time. You must use materials in stages like barrels and weights to get the iron black ball to the exit. By digging holes, you can avoid ground enemies, get to different places, and greate paths. All of this works together to create an astounding puzzle game.
For a GB game, you won't mind the graphics or sound. The sounds are quite catchy and the graphics are not sketchy. Hey, that rhymes.
There is also a multiplayer option where you can link up and do a head to head challenge.
In the end, you'll love this game.