I have one along with a M3 miniSD. Plan to get an M3 Lite soon :)
1) I bought a Superkey for it and I prefer to use it, I've noticed sometimes it won't boot 100% of the time with the Passcard3 (maybe just an error on my part)
2) NDS compatibility is pretty good, its a tiny bit slower than the M3 at loading games but it gets the job done. Also, like mr_hanky said, GBA compatibility isn't the best.. it plays a lot of games but some games just don't work and a few seem to slow down often. I bought mine from http://www.getyourgameshere.com
