If I had a D800 or D800E already, I would probrably not upgrade, but as I am looking for upgrading from DX to FX, yes, the new D800s is a real contender for me (need to start saving $$ now). For me and myself only:
One stop better low light / Better native ISO settings --> amazing features, if confirmed.
AF improvements --> another very good news indeed.
Lighter the old predecessors --> this is always more than welcome!
GPS --> that's also great for me, once I travel a lot and would benefit a lot of the GPS labeling feature.
36MP --> love it, especially for being a 24MP DX user myself, and being used to it.
sRAW --> is a good addition to me, making it a more versatile and flexible camera. I guess it would be a 9MP sRAW file??
Expeed 4 processor --> I'm curious about it.
No AA filter / improved moiré software --> again, I'm curious about it as well.
Higher resolution LCD --> another plus for sure, but not essential.
5 fps --> another good add, but not so critical (I don't do sports and don't need more than that at all).
WiFi --> fun, but not key for me at all, so no WiFi means nothing for my style, as I would not use it.
4K --> I really don't care, as I do not do videos.
etc...