I have been shooting D800/e now since March, and I never shot in a studio with controlled lighting. I have shot landscapes as well as birds in flight...the full spectrum of demands on a camera body.
When I am processing the images, I am still amazed at the level of details compared with my D300 and D700 bodies that I used to shoot that full spectrum.
When I see a note from someone saying they cannot shoot the D800/e in situations that they can with a D700 or D300, I just smile...because I know it can be done. I do it every week. Did it take me a while to master the D800? Yes. And it is worth every second of that time.