In my opinion when paired with a GBP, it's much preferred over the stock GameCube controller or any SP model. I even prefer it over the excellent Hori digital gamepad for the GameCube, since the GCN's button layout that is copied just isn't a great match for many Game Boy games.
Verm3 wrote:The Critic states in his Sega Rally review for the Advance, that he uses a Game Cube Gameboy player for playing Advance games. How does he play GB and GB colour games?
While I don't know what his preferred hardware choice is for playing those games, the Game Boy Player is backwards compatible with original Game Boy and Game Boy Color games. So if he owns one of these accessories, he can certainly play older Game Boy software on it.
All Game Boy Advance handhelds share this trait as well, except for the short lived Game Boy Micro which eliminated the Z80 processor that was necessary to enable BC (A trait shared by the backwards compatible DS and DS Lite which could play GBA games but not GB/GBC games).