I'm pretty satisfied with my GBP, I've found it extremely easier on the eyes and fun to play with. I've also tried linking up my GBA with the GBP and it works wonderfully with Mario Advance ( Super Mario Bros. 2) It's nice to have multiplayer that doesn't require more than one cart to play.
It does look really nice on the TV set, Metroid Fusion especially. it's very comparable to the SNES Super Metroid, I hope Metroid: Zero Mission will look just as nice as either of those mentioned.
Golden Sun I find looks really sweet, like it was made for the big screen

and the audio helps coming through the TV. I really want to get Lost ages.
Games like Zelda oracle of ages and Links awakening look good, Although the original Links awakening isn't nearly as well presented compared to it's game boy color counter part, but it's still pretty darn close.
I would like to play 4 sword, but there's that issue of needing more than one cart to play *sigh* Although I do own the original lttp for snes.
And Breath Of Fire 2 looks as well as it's SNES counter part, the only minor issue is that the sound effects in some areas aren't nearly as well produced compared to the original. But it excels everywhere else.
when it's all said and done.... I love this thing