It is smaller and lighter.
Its sharpness leaves nothing to be desired, even on the D800, although I prefer to use it on the Df, to which it fits very well.
At f/2.5-f/2.8, sharpness and above all contrast is a bit less than above, as with most "old" lenses. But you get wonderful bokeh in compensation. I use that aperture for portraits.
Otherwise, its optical qualities are such that you will not notice its age. Compared with the Zeiss 135/2 which I bought the very same day, you would not notice the 1:8 ratio in price. The Nikkor is slightly less contrasty, esp. wide open, and I would expect a lesser resistance to flare. I have not tested this particular aspect, but I do not care: in practical use, the lens never misbehaved.