No, it is not just NAS. The D7000 is indeed miles better. I agonized like you and then went for the D5100. I used it for a few months, loved the sensor quality, but kept gravitating back to looking at the D7000.
In January I bought a used D7000 from a nikonian and love it! I have sold my d5100 now (thankfully, before the recent Nikon price drops, so didn't incur a big loss).
Pluses of d7000:
(a) Hugely better viewfinder. It isn't quite as large as the old viewfinders in Nikon film cameras, but it is much better than the tiny one on the d5100. My wife used to complain about having to squint for the d5100. I too can't compose well while squinting like that.
(b) Pro features like dual slots, custom shooting mode, longer battery life, ability to meter and focus with AIS lenses (I have a 100/2.8 AIS that I sometimes bring out for portraits)
(c) much better ergonomics and feel (if you shot with old film SLRs you will know what I mean).
Just the viewfinder and the feel alone make it worth the extra $$ for me.
Try buying a d7000 used around here; if you don't find it a worthwhile you can just sell it again without a huge loss.