I had never heard about these devices till today. As someone who is loathe to carry around a laptop at a gig, I have always felt like I was missing out on being able to get VST quality sounds.
This is a device that specifically addresses those concerns: you can directly load VSTs on to it and even effect plugins. Think about it, studio quality delays and reverbs with the Kemper.
Alternatively, if you're into synth sounds, you could run spectra sonics omnisphere at your gigs. Or Trillian. Or if you need a backup for your Kemper, Amplitube or Guitar Rig or Revalver.
and... It has been Discontinued! Very difficult to find one online for sale even.
My curiousity was intensely piqued, so I did some searching and found a used one for a pretty good price. Will let you guys know what I think when I get it at home.