its a pretty slow (focusing) lens if ur buying the nikon mount version. other than that its a pretty good lens for the price and manual focuses rather well... i'd say the focus ring feels much better than the canon 50mm f/1.4, as it more 'loose' hence easier to turn.
Not v sure if this would help as they are not portraits...
I have 2 pics in my portfolio that are taken with this lens on a D100 on manual focus
its the pics titled 'strings of melancholy' and 'limelight' http://b.1asphost.com/kgston/photos
err i onli got 17mb of bandwidth/12hrs so try not to flood the server^^