I was up at Elderly's on Friday and I got a chance to play around on one. My impressions were -- it sounds great, but it was VERY hard for me to play. 1. its string courses are so close that chording was nearly impossible for me. Whipping off a fiddle tune wasn't too bad once I could convince my brain that, though I was holding a mandolin, I had to finger it for the guitar. I constantly reached for the mando chords and scales.
It wasn't anything like a baby Taylor or a Papoose -- it really much more approximated the mandolin sound. I would highly recommend trying one -- it could really add sparkle to a set or recording.