The 50/1.4 Zeiss is among the less coveted Zeiss lenses, and it sort of makes sense as there is a Nikkor match that isn't all that bad either. Given the price, I think it has bragging more than practical value for a large majority. The Zeiss 85/1.4 is said to be noticeably sharper than the Nikkor. Even so, I have never felt let down by my Nikkor AF-D version, and am not about to give it up for a manual focus Zeiss twice the price. I am sure that also applies to most Nikkor 50/1.4 owners.
Where the Zeiss lenses make more sense would be where a comparable Nikkor does not exist, e.g. the Makro-Planar 50/2 and 100/2, and some of the wide-angle primes which are markedly better than the offerings from Nikon. I have shot with the 100/2, and must admit that it is a wonderful optic. I feel no urge to fork out $1600, or whatever it costs nowadays, for a manual focus lens, but if it ever came in an AF-S version, I'd be right in front of the queue.