First impressions of the D600 (renting it right now): Feels like a slightly bigger D7000 (obviously since the control layout is very similar). Not as quick to lock on focus in low light as the D700. But when it does the photos are incredible. Haven’t shot it in daylight or the studio yet, but I expect big things. One thing that struck me was how superior the live view is now, especially when using it to aim and take photos and not having to use the view finder. I never had luck doing it that way before, especially on the D700, but with the D600 it’s very effective. And did I say the image quality is phenomenal? ISO 3200, WOW.