Image quality results have been added to Canon EF 100-400mm f/4.5-5.6L IS II USM Lens review page. I think that you are going to like what you see.
Here are some comparisons that you might find interesting:
Compared to the Canon EF 100-400mm f/4.5-5.6L IS USM Lens
Compared to the Canon EF 70-300mm f/4-5.6L IS USM Lens
Compared to the Canon EF 200-400mm f/4L IS USM Lens
Use the Image Quality Tool to create your own comparisons. Hint: Zooming your browser to a higher percent can make the differences clearer on some displays (Try CTRL+, CTRL- and CTRL-0 to reset). Share your thoughts in the comments section below this post.
B&H has significant quantities of the Canon EF 100-400mm L IS II USM Lens arriving regularly. Demand has been very high.