I've played on these a few times and was very impressed. The drum beats and built-in bass lines are really cool for practice/ jamming and DON'T sound crap, suprisingly. It also has a phrase trainer which is probably very handy for learning parts. Apparently you can record a few seconds of a song in (it's got an AUX minijack) and slow it down or change the key to play with and learn how the song goes. Don't know how well that works because it's not exactly something you get to try in a shop but it seems like a cool feature.
The sounds are also very good for what it is (a digital modeler), quite similar to the KORG AX1500G I had a few years ago, maybe a bit warmer. For those interested it is pretty good at metal/ shred-type sounds too. I'm told the bass guitar tones are good, but I didn't get to try that.
BTW, found this site: http://korgpandora.com/#start
Seems to be official Pandora site.
There's a new model too, the PX5D. Looks tasty and it's got a built-in USB Audio interface (basically it's a soundcard too). Plug in and record with all the onboard sounds.