Even on my crop frame D300s and at a small distance from the subject this beautiful lens renders lovely out of focus backgrounds! This was set to f2.8. Taken during our Sunday cycle through the countryside.
Just to give an idea of how sharp this lens is, here is a pic also taken on Sunday with the 85mm f/1.8, and included is a 100% crop of the windmill section below that:
One last point, if there is any distortion from this lens I am totally unable to see it! :-)