LensRentals.com has completed their initial tests of the Canon EF 11-24mm f/4L USM. They have come away extremely impressed and they look forward to further testing and most importantly, making images with it.
As you can see, the center t 16mm has an even higher resolution than the two extreme ends, although the edges are just a bit weaker.
But all of that is hair-splitting; this is a remarkable lens. Canon made the widest full-frame rectilinear lens available, and made it with superb image quality throughout the zoom range. Once again, hat's off to Canon's lens designers.