If I would buy it again ? YES !!
First of all, I have bought a 5D III due to it's strong points and has nothing to do with the D800. It was from day one that I knew that the D800 is a fantastic camera, but comparing strong and weak points overall they are really on the same level, but the 5DIII strong points are much more important to me. Dpreview shows that the 5DIII is even better than I thought compared to the D800.
After reading the comparisons with the 5DIII and comparing the graphs which already include the 5DIII measurements, confirms that the D800 is a great camera, but the review also shows how impressive the 5DIII is. It will be interesting to read the 5DIII review when ready.
Two days ago I was processing with ACR 7.1 a 5DIII ISO 25600 image of an Aztec statue in a low lit museum handheld, and was really impressed at how easy it was to clean up the image without much detail loss. Yes, the detail starting point of the image was lower compared to an ISO 100, but the noise reduction managed to remove the noise easily without any extra detail sacrifice.
This made me think, the DXO measurements of RAW data shows that the 5DIII, D800 and D4 have similar noise capability, with a near negligible edge for the D4 at some ISO's. When we look camera JPG images, the 5DIII shows that it manage to perform even better compared to the competition and we always used to think that Canon JPG engine is just better. I was going to open a new thread about this, but after seeing Radiating post, I think it is good to mention it here because it is exactly what I was thinking about. Is it really the characteristics of the noise of the 5DIII which makes it easier to clean it up that well with software, rather than just the Canon JPG engine being good ?
In short, I am really impressed with this camera and I am still at early stages with it. It is true that there are some stupid omissions, of which I hope some will be fixed with a firmware update. Also, I think that the 5DIII should be priced similar as the D800.