Nikon D4S: a hands-on review with comparisons to the D4 by Tom Grill (Web | Blog). As aways, click on images for larger view):
The lineage of Nikon flagship models, the D3, D3s, D4, and now the D4s, are absolute workhorses, and best of breed at what they do. In the hands of a working pro, this camera line represents dependability and exceptional image quality under the worst circumstances you can throw at it, qualities that have endeared themselves to Nikon users since the original Nikon F. At first glance, the jump from the D3 to D3s appeared to be a greater difference than that of the D4 to D4s. We seem to be getting to a point in their development where the changes from model to model give us less to shout about. I think this says more about the confidence we are experiencing with the camera we have in our hands than it does about the advancements made to improve it.