I am a professional photographer and had problems with the left focusing issue on a D800. I've tried to get it fixed a couple of times without success during the summer. But I can confirm now that Nikon UK finally managed to adjust the focus points properly and the camera works perfect now.
For my camera, I opened a support ticket with Nikon. I also have a general center AF accuracy issue that is not widely reported. They told me to send the camera in to a Nikon Service Center. I haven't done that yet, hoping for a recall.
My understanding is that Nikon has acknowledged the problem as being a sensor mounting problem. The effected units would have to be sent back for re-alignment. However future units shipping from Nikon has now been corrected. My advise would be to determine where the serial number break is and make sure your order includes units supplied after that break.Heres where you learn more about the problem. http://nikonrumors.com/2012/09/25/update-on-the-nikon-d800-left-focusing-issue.aspx/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NikonRumors+%28NikonRumors.com%29&utm_content=Google+Feedfetcher. Now my own opinion based on using my D800 which is in fact affected by this issue. For me it is not an issue. I shoot landscape and never use the farthest focal points. Never have because that is where all cameras will struggle acheiving perfect focus. I refer to the 51 point sytems or higher. If i was dependent on using these points however i would do all i could to insure the camera was focusing to the best of its design capabilities. I stand apparently in a small group with this opinion but i have the problem and i simply dont care. The camera takes amazing pictures and i achieve spot on focus without deviating from my normal methods. Please keep in mind however this is my opnion only and most will not agree.
All I can say is that I spend more time going back and forth to Nikon Service center, testing AF and yelling at their management than making pictures. If they had a fix I would know. They don't seem to have one for sure because they have not yet exchanged my camera for a one thet works for sure. After hours of testing, it is obvious that the AF sensors are not precisely aligned and that Nikon service center just tries to fix this mess by software or lens recalibration but this is not a repair, it is a sort term fix, quick and dirty.
Save your money and time: NIKON LACK OF PROPER REACTION IN FRONT OF THIS ISSUE IS THE WORST SiGNAL TOWARDS ITS CUSTOMERS
I don't know whether the problem has been fixed by Nikon. But I can say that the D800 I recently purchased does not exhibit the focus problem. From my reading it seems that problem is most prominent when the photographer used a wide angle lens. I tried it with my wide angle lens (10mm-20mm Sigma) and observed no problem and no vignetting either. All in all, I am happy with my camera and I am glad that I bought it when I did.