I've owned one. It was my first bike. Great bikes, I love them and will eventually buy another one.
What to look for: steering head bearings can go bad, the old style bullet fuse box under the seat can rust out and err... I believe that's about it. Nothing unusual about them. Gas tank is kind of small though.
Folks run them up to 60 or 80 thousand miles without problems. There is a Radian owners group on Yahoo, join up and bask in their knowledge. Derek at
Motolab can get you hooked up with parts, including an awesome clutch setup.
[url=http://www.motoblag.com/blag/]Practicing the dark and forgotten art of using turn signals since '98.[/url]