My cousin owns one, and I've test ridden a couple. If in good condition, they do feel solid as a brick, strong as an ox and can be like riding a low-flying missile along a country rode. On the ones that I rode, the handlebars definitely had a distinct buzz around 60 MPH, and the gearbox wasn't the smoothest, though the particular ones I rode weren't new and may have been in need of some attention there. The engines do produce alot of heat. They don't seem to have the "soul" of an airhead though, but are very good at eating up miles of roadway.
My cousin's bike has over 160K miles on it since he bought it new in 1985. I think that the only thing that he's done to it has been
1. Replace transmission (these bikes had a certain weak spot relating to a bearing on an internal jackshaft in the transmission that emits a distinctive rattle when it is wearing out. It is very time consuming ($$) to get the transmission torn down far enough to replace it, and most folks without all of the tools simply replace the transmission for less $$
2. The final drive needed rebuilding just this summer @ 160K miles.
3. I think that he has replaced the clutch on the bike one time.
4. Aside from normal maintenance, (oils, coolant, throttle body injector sync, valve clearances (these require shim replacements but not very often), tires, etc. it has been a fairly low maintenance, ride-n-go bike.
5. I still like my Kawasaki Concours a bit better, though.
