Conclusion: Given its heritage and flagship status, it was clear coming into our Nikon D4S review that the question we'd be looking to answer wasn't so much whether this was a great camera, as how great it might be.
Pros: Excellent, tank-like build quality, Same great ergonomics you know from the D4, Big, bright viewfinder with 100% coverage, Dual card slots, Excellent overall image quality, Outstanding low-light capabilities, Very good dynamic range, Superb performance, Even faster burst speed with continuous AF/...
Cons: Fairly minor upgrade of the D4, especially if you only shoot RAW files and aren't a movie shooter, Large, hefty body (but that's par for the course in a pro camera), XQD card format hasn't been widely adopted (but you can still opt for CompactFlash cards if you want a more broadly-accepted format...
Summary: The jump in continuous shooting speed of a frame a second might not sound like much, but it will certainly be good news for professionals, while the similar improvement in AF performance will also be welcome.
Pros: High ISO performance; Improved continuous shooting; Enhanced video performance
Conclusion: This camera is stunningly good, and arguably the most advanced DSLR ever built. If you could go back in time to show photographic pioneers like Eastman and Daguerre just how far we've come, you'd have to take a D4S with you.
Conclusion: The Nikon D4S is an evolutionary rather than revolutionary continuation of the earlier D4 model. But that's not to take anything away from it: as full-frame professional cameras go this is as good as they come.
Pros: Almost indefatigable battery life, autofocus improvements for outstanding performance, great image quality, well designed
Cons: Big, heavy, expensive, still no USB 3 out, minor update over earlier D4, Canon 1D X has faster burst rate
Summary: In terms of handling, little has changed since the original Nikon D4, though the few refinements to the D4S's AF and shooting rate are enough to make a difference. The autofocus system on the newer camera is one of the best I have ever tested.
Summary: The Nikon D4s is an evolutionary, rather than revolutionary, update of the two-year-old D4 camera, adding a raft of relatively minor improvements that add up to make the D4s a slightly better camera than its already well-appointed predecessor.