Well, I "upgraded" because of 2 year warranty and better AF, and for now it looks like I made a good decision.
You can read here my observations from the past 24 hours of owning this camera:
http://nikonites.com/d7000/25209-upgrade-question-4.html#axzz3CRCi06QR
I think that AF is much better, but low noise performance is the same as D7000, or maybe just little bit different, I need to adapt.
Other than that I like some of the new features in the interface, 1.3 Crop Mode is useful for me, I would call it an upgrade, it just depends how much money you are willing to spend for a teaspoon of progress.
I gave my D7000 and 340 Euro more, which is a lot for me and my photography, but my D7000 AF was very bad at low light, and yellow light, so I did not feel it was working well. Other than that, there is almost no difference in IQ and dynamic range, 24 mpx is nice option, just I do not see any difference compared to 16 mpx.
If I had this AF accuracy with D7000, I would never sell it and pay this kind of money for D7100. It is a great camera, but D7000 is still very good, beside that faulty AF module...