I've used this lens for 3 days on the NEX-5.
My preliminar and unscientific conclusion is that wide open (f/1.7)
the lens performs reasonably well,and the bokeh indeed is very soft.
It is also a lens that I'm inclined to use for B/W photography:
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Here follow some - again unscientific - test shots (no PP, except resizing and using a clone tool for the f/16 pictures )