The bokeh probably won't win any awards, but it's not really bad. It resembles bokeh from the 28mm f1.9. You can see another sample (second picture) of bokeh from this post I wrote couple years back. But, at f5.6 to f8, the lens is very sharp. Even at f1.9, the lens is usable in most situations, but not very contrasty at this apreture.
When I bought this lens, it wasn't very expensive, and is quite a common lens. I seem to pick one up once in a while at the photo show and now have three or four of them, of different mounts. If you come across one of these beauties (they are extremely well made), be sure to test it out.
Self Portrait - NEX-5N & Vivitar 35mm f1.9. Click for larger
Bokeh - NEX-5N & Vivitar 35mm f1.9 @ f1.9
Window - NEX-5N & Vivitar 35mm f1.9
New and Old - NEX-5N & Vivitar 35mm f1.9