http://www.imaging-resource.com/PRODS/nikon-d4s/nikon-d4s-shooters-report-part-ii.htm

If you're coming from an enthusiast-grade camera, and you're prepared to accept the added heft of a pro shooter with a body that could hammer in tent pegs, you'll doubtless find it to be a spectacular upgrade. The D4S pairs truly great image quality with superb performance.

http://www.imaging-resource.com/PRODS/nikon-d4s/nikon-d4sA.HTM

v1.20 firmware

• Commander mode can now be selected for Custom Setting e3 (Optional flash) when an optional SB-500 flash unit is attached. *
• The Auto and Flash white-balance options can now be used with the LED light on the optional SB-500 flash unit.
• Auto white balance is now more consistent.
• There is no longer a limit on the number of shots that can be taken in a single burst at shutter speeds of 4 s or faster when a continuous-release mode is selected in exposure mode S or M. *
• There is no longer a limit on how long the shutter can remain open when “Time” is selected for shutter speed.
• We have changed how focus points are displayed in the viewfinder if the camera is rotated between “wide” (landscape) and “tall” (portrait) orientations with Focus point and AF-area mode selected for Custom Setting a10 (Store by orientation) and different focus points chosen in each orientation. We have also changed how focus points are displayed in the viewfinder if a lens focus function button is pressed with AF-area mode selected for Custom Setting f19 (Lens focus function buttons).
• Some help text has been changed.
• The following issues have been resolved: 
  • If the user focused using the AF-ON button before shooting in continuous-release mode, the frame rate would drop under the following conditions: AF-S selected for focus mode, Single-point AF selected for AF-area mode, Focus selected for Custom Setting a2 (AF-S priority selection), and AF-ON only selected for Custom Setting a4 (AF activation).
  • When an AF-S NIKKOR 800mm f/5.6E lens was attached, “Err” would be displayed in the top control panel and pictures could not be taken under some exposure conditions.
  • Images would sometimes fail to display correctly during image review if playback zoom was used while the memory-card access lamp was lit.
  • Images would not clear from the display if an optional WR-1 wireless remote controller was used with On selected for Image review in the playback menu.
  • The camera photo info display would not show the correct range for pictures taken with an optional flash unit in distance-priority manual flash mode (GN).
  • When pictures taken using a PC-E lens were viewed in Capture NX-D and other Nikon software, the Metadata would list the lens as type E rather than type D.
  • The photo information display for movies, movie stills, and photos taken with the Silent shutter-release option would sometimes list incorrect values for shutter speed, aperture, and ISO sensitivity.
  • If the camera was connected via HDMI to 4K a compatible TV, neither the camera nor the television would display menus correctly.
  • Volume sometimes could not be adjusted if indicators were hidden during movie playback.
  • If both XQD and CompactFlash cards were inserted in the camera when it was connected to a computer, the computer would not recognize the XQD card.

http://downloadcenter.nikonimglib.com/en/download/fw/138.html

Officially discontinued

http://www.nikon-image.com/products/slr/discontinue_lineup/