Guys None of us can even guess the battrey life , why not wait till tests have been done ?lol.
First time this chipset and screen been used......
It is fun to guess
Plus it will be a while till we get the "jest" of how the battery is until the public get their hands on the device, so we might as well guess away!
Also we can get a rough idea pretty much of what it will be like considering there are similar mobiles out with similar screens etc. e.g. galaxy nexus, galaxy note (higher res. etc. though) and then the XL (it has the dual core krait S4, which is very power efficient) and the X.
AFAIK, there isn't anything that special about the screen, just a standard 720P 4.8" screen with a pentile matrix that has apparently been "tweaked" like the SAMOLED pentile screen on the HTC one S.
And if it is anything like what we know of the current phones regarding the camera then it is pretty certain that the eye tracking will kill battery life as it will be pretty much constantly focusing on your eyes and essentially always on.
It won't be anything ground breaking, will still need to charge once every night or 2, just like with every smartphone.
EDIT:
Well tbf it doesn't offer a huge amount over the GN just like the X/S etc.
Has a great screen with better software, better design.
Only areas, which will be better by a noticeable amount is the camera, battery probably (out of the box), lots more storage and much better hardware (but in real world usage, you won't really notice a huge difference, only in the willy waving benchmarks

)