As above really. Canon have replaced their original 24 - 70 L with the MK II and it's supposedly their sharpest ever lens and certainly wipes the floor with the Nikkor 24 - 70. The Nikkor is pretty much identical to the mk I L 24 - 70 Canon - I know as I used it on the 5D mk III. Basically it's pretty soft in plenty of places especially at wider apertures and plenty of CA at 24 - 27mm. It has pretty much the same faults as the original Canon. In fact it is exactly identical in every way - including the way that the lens goes out at its wider end and flat at 51mm. I'm not saying it's a bad lens - it isn't but amongst the so called Trinity it's the weakest. It's sharp in the middle but generally far from it in the corners and even well into the frame on the D800. You don't need to pixel peep to see it. Sharpening using USM or smart sharpen in CS6 helps, but it is a professional lens and it is lagging behind Canon's 24 - 70 L II.
Why not get one up on Canon by producing an AF-S 24 - 70 f/2.8 VR? Any sign of it?