It's the 28mm f/2.8 AIS that has the full bore Nikon goodness added to it: 9 elements, CRC, very close focusing, no distortion. I don't know anything about the f/2 lens though.
If you do look for the 2.8 AIS, then check the rear lens element. It protrudes beyond the metal mount, and people who plop their lenses down without a rear cap on WILL scratch the center of the rear element. It's happened on so many used 28mm f/2.8 AIS lenses that I've looked at and returned, that I finally just bought a brand new one from B&H.