This is my third DSLR, starting with a D70 then a D7000 a couple years ago (not counting a Nikon film SLR used for decades before that).
Rather than rehash the technical features, I'll summarize in saying that the gorgeous big viewfinder (compared to a DX format SLR) makes all the difference in the world. It is an absolute joy to compose an image this way. Like taking the blinders off. You won't realize the difference until you try it.
Compared to the D7000: handling is essentially identical (a good thing); ergonomics and grip feel more solid, and shutter/mirror delivers a louder (more authoritative?)
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