I'm not sure what "real world" means? Does it mean: situations where there is no benchmark of comparison? Is the stadium roof so badly out of square or is it the lens distortion? The 1.8 sounds very impressive. They must be very bright viewing. I don't think the speed is as important as it once was with ISO ratings approaching the stratosphere. One thing for sure, lens quality has not kept up with the capabilities of the bodies. It is nice to see an effort toward improving quality. Almost reminds me of the Summicron, Planar.
The new Nikons are unquestionably great cameras. Apart from "professionals", who uses anyone of these cameras enough to justify spending the extra $? The other issue is the lenses. I have been using cameras and lenses for over 40 years and I think lens quality has actually regressed at the professional end. Sure we have better AF, but most lenses now need serious computer rejigging to compensate for distortions and other aberrations. When will Nikon create a standard lens with the corner to corner sharpness and a distortion free horizon?
I'm surprised no one commented on the fact the D4 requires a new kind of battery. Besides that, it took Nikon long enough! Anyone with a D3, who tried out a D7000 would find a lot to like about this smaller, lighter body with better low light. I hope the D4 is even better. I am also surprised the D4 stuck with CF cards. Most computers come with slots for SD cards now. I'll wait a bit, when the price comes down. I sold my D3 and D3x in anticipation.