I own the D700 and D7000 and have owned the D300. The D7000 is, to me, clearly superior to the D300. I never liked the look of D300/D90 images, but of course that's highly subjective.
I've had my D7000 for a couple weeks now, and I'm shooting almost exclusively with it these days to get more familiar with it. I'll have something major on Friday that will allow me to put it through some heavy paces. Its big brother will be on hand to do some heavy lifting, but the D7000 is strong on its own. It is well built and feels like a compacted D700/300. It has the same magnesium alloy build, just smaller.
The viewfinder appears the same between the D7000 and D300, and the D700's viewfinder space is clearly better than both.
The D7000 has an array of things I like, including the leveling feature present in the D700. The focus mode button change is welcome, and stops me from accidentally switching from S to C or vice versa. The sensor goes down to ISO 100 natively, which looks terrific. It can be nice to have a small but solid camera, rather than a larger one like the D700/300.
It still looks good at ISO 800, which is important to me. The autofocus may not be as strong as the D700/300, but it's still very good. I only use the center point, so it could have a hundred autofocus points and it would be more or less irrelevant.