I own Unplugged, but, uh, have yet to play it. How is it different?
It's similar to Blitz except instead of power ups and juggling multipliers, you use four buttons to play notes instead of two. If you play a track well for a while, it starts playing itself and you can move on to a different track. So instead of juggling for multipliers, you're juggling to keep all of the instruments playing simultaneously.