There are a few advantages to the Super Game Boy, and one is that games designed with it in mind have a few extra features. Like Pokemon Red, Blue, Green & Yellow all have their own custom borders and just like in Yellow each city has a different colour sceme (Pewter is Grey, Cerulean is Blue. Vermillion is Orange, etc) it adds abit to a game originally played in black and white. Games like Donkey Kong have enhanced music colour and other features not available by just playing it on a regular Gameboy. Here's a list of games that the Super Game Boy benefits from:
http://en.wikipedia.org/wiki/List_of_Super_Game_Boy_gamesNow there are some drawbacks to the Super Game Boy. Since the hardware inside the cart is in fact an original Gameboy with a few modifications, it can't play Gameboy Colour exclusive games like Pokemon Crystal or Donkey Kong Country pretty much any clear Game Boy Colour cart. It can play the black Gameboy Colour combo carts thou with enhancements. Second, it doesn't have an EXT port which isn't too much of a gripe but some people wanted one. The Super Game Boy 2 in Japan had one but they are abit rare.
Even with it's few drawbacks it's actually something really fun to use, playing Gameboy games on the big screen with a SNES controller is much better and the enhancements give it just alittle bit of a new way to play your favorite Gameboy games.
Now I do have a GameBoy Player as well and it's really fun to use for all my GameBoy Advance games and any game in my Gameboy Library, I just wish they could have built in those enhancements with it as well.