How much of a piece of crap is this exactly?
I don't know, but I don't remember it being any good. Probably a software emulator compared to the GPB's hardware emulation.
Fun fact: the following GC discs have software emulation on them.
Animal Crossing (NES)
Fight Night Round 2 (SNES) (unconfirmed, but how else are they running Super Punch Out?)
Zelda OoT Master Quest (N64)
Zelda Collector's Edition (NES, N64)
Pokemon Box (GBA)
Naruto Collection (Japan, hard to find but not necessarily worth a lot of money) (GBA)
Then of course there's the Midway Arcade Treasures discs etc.
Another fun fact: Zelda Collector's Edition contains the full Wind Waker disc for the demo. People have corrupted it to start at the beginning of the full game. I think you can't collect items so you can't beat it, though. A hack could probably fix that but WW is around $20 so it's not worth anyone's time to investigate.