Put the two model together, without the model numbers; you will be hard press to see the differences ;) They look exactly the same!!
So what is so big deal about this NEW D7100?
According to Nikon...
It is lighter than the D7000 (780 g), the D7100 weighs a mere approx. 675 g or 1 lb 7.8 oz (body only).
The D7100 come with a larger 23.5 x 15.6 mm, 24.71 million DX CMOS sensor, the D7000 only command 16.9 million pixels.
The D7100 employs an image sensor unit designed without an optical low-pass filter to take full advantage of the high resolution achieved by its high pixel count. Just like the D800E!!
That, to me is the ONE of the MOST IMPORTANT improvement in the D7100.
Where auto focus prowess is concern...
D7100 - Nikon Advanced Multi-CAM 3500DX autofocus sensor module with TTL phase detection, fine-tuning, 51 focus points (including 15 cross-type sensors).
D7000 - Nikon Multi-CAM 4800DX autofocus sensor module with TTL phase detection, fine-tuning, 39 focus points (including 9 cross-type sensors).
In theory at least, the D7100 will AF FASTER than the D7000!
Look at this sample photo at the Nikon site!
This shot was taken by photographe Koji Nakano with a D7100 and a humongous AF-S NIKKOR 500mm f/4G ED VR lens at f/5.6 and 1/2000 second. If you are not very impress, look at the blow-up below!!
You want closer?
All photos © NIKON.
That kind of AF prowess AND SHARPNESS from a US$ 1,199-00 DSLR body is mind boggling!
What about the lens used for those shots, you ask...
B&H New York can let you have one for.... $8,399.00 US$ ;)
What are you waiting for?