I got my GB Boy Colour today. It works fine. Contrary to Maz'Hoot one, mine is turning off the speaker when I'm using a headphone.
The speaker is not correctly wired, only the right channel is connected. Hopefully, with a headphone it's correct for both channel. Maybe it's possible to fix this, but I intend to use it mostly with headphones so I don't really care.
I've put a nanoloop image on my GB USB 64M card, but it's not working (black screen). I've also tried the image on my "real" Nintendo gameboy color, and I can't make it work either. But the same image is working with a GB emulator on my PC, so, I don't know. It seems some people managed to make nanoloop work on this device: https://www.youtube.com/watch?v=tw3HD5lUWUw He talks about a mGB ROM, maybe it's needed to make nanoloop work (or maybe not: http://nanoloop.com/midi/mgb.html). I don't use nanoloop so I'll probably stop here at the moment. [edit: on the video, it's not nanoloop in fact, only mGB, which can use a nanoloop cable to connect to the PC)
Otherwise this GB Boy Colour seems great. It's just a pity they used a different screen ratio than the original GB so the games will look a bit distorded. There is much noise when I'm using a real cardridge (either for lsdj or for a normal card game), but I suspect it's because my batteries are low, or because it's rechargeable batteries. On the built-in games, the sound is OK. Like you can read on several website, there are 66 games, but they duplicated three times, for an unknown reason (probably to make it look there are more than in reality). As far as I've seen, it's only old, 2 colors, DMG GB games.
On the package, it's written 2006, so if it's for the year, I guess it's no longer produced, only an old stock.