I have updated the Canon EF 24-70mm f/4L IS USM Lens review
to address the focus shift this lens exhibits. Scroll down the review
page until you see the sheet music image. Then start reading two paragraphs above that example.
The bottom line is that there is a rearward focus shift, but it is not likely to significantly affect many uses of this lens.
I continue to use this lens for many of my general purpose needs. The image shared in this post is one of my recent 24-70 f/4L IS captures. See it larger and read more about the capture here: Little Storm