I had the f/2 version and contrast was a little low at f/2 but was plenty sharp and by f/2.8 was great.
When I put it on a Nikon V1 it was also very sharp stopped down a little which is quite impressive as with the 2.7 crop factor that is some magnification going through the lens.
Focus wise it was noisy (as all AFD lenses are) but accurate.
I guess it depends on how you plan to use it as I suspect the new f/1.8 version is better in every respect except for size, I hear it is sharp wide open so if you plan to shoot in low light maybe that is the way to go.