I think this is just a rerelease of the first Joysound with a better microphone.
I tried running the first through the USB Loader and it kept losing my subscription ticket as soon as I'd bought it. I'm not the only one either. If you really want to get it, I'd go for the WiiWare one. Hasn't glitched up once for me.
Oh, and the online catalogue for this comes from one of the biggest karaoke chains in Japan. So it goes without saying that the selection is *huge*, including tons of English songs. As long as you have a menu translation, you're set.