Pros: None... really!
Cons: Doesn't belong on a GBC, you can't distinguish between the ball colors
Don't get me wrong, I absolutely love this game! I spent many hours in college playing Bust a Move on the Playstation with my roommates. My reason for not giving this game a good review isn't because the game isn't good, it's because the GBC just isn't the right way to play it.
The object of the game is quite simple. You have several different colored balls at the top of your screen, and you need to keep the number of balls to a minimum. Characters from Bubble Bobble load up your cannon with a particular ball. You fire this ball at any identically-colored ball at the top of the screen, and if you can create a group of three identical balls, they'll be destroyed. You can also execute combination moves by having various balls "hang" from one colored ball; when you destroy this ball by firing two of the same colored balls at it, you destroy the entire group. This results in more balls appearing on your opponents screen.
Yes, it's quite a simple concept for a game, but this game fails miserably because it relies on colors. On the GBC system, it's nearly impossible to distinguish between the five or six different colors. Lighting conditions are never consistent on this system, because one invariably shifts around while playing, and this makes it very difficult to see the colors. Even using the screen magnifier and lighting unit doesn't help.
I played this game for about 3 minutes on my plane flight to LA, and I got so frustrated that I just had to stop. Please, do yourself a favor... if you really want to play this game, just get it on the Playstation or even the N64. Your eyes (and nerves) will thank you. It also doesn't support the link cable! One of the greatest features of this game was playing against your friends, and on the GBC it isn't there!