What are you upgrading from? I upgraded from a D80 to the D4 and WOW love that camera. Amazing thing. On my last 2 trips I didn't use flash a single time. So nice to be able to just crank up the ISO and not have to worry about noise and just keep shooting. With the D80 I had to start using noise reduction already at ISO 800 and totally fall apart at 1600 the D4 I might have to use NR at 3200.
So nice to have the freedom. I'm sure you will enjoy that camera A LOT.