My favourite flickr photographer and very good flickr friend, Junku Newcleus, makes magic with the Summarit 50 f1.5. He uses it with Neopan 1600 and it seems that the lens combines very nicely with that very contrasty film.
The bokeh is difficult, and it reminds me of the bokeh I have seen from the Nikkor 50 f1.4. But then most photographers do not use this lens (or the Nikkor) for the bokeh (there is the Noctilux for that).
There is one occasion where I would use the lens for bokeh, and that would be if I wanted to take a photo of a drunken person and I wanted to convey the sense of nausea that visited him after the intoxication.