I started with a D70, then upgraded to the D200 and came to the D300.
This is a very nice camera body, the build just says quality. I also have the MB-D10 battery grip and really like it in comparison to the D200 battery grip. I appreciate a camera with a little heft to it. I carry a 50 lbs tool bag around so this is a dream even with my 70-200mm lens. I've picked up the competitors camera bodies in this price range and quite honestly they feel like toys. I'll agree with some of the not so favorable reviews in the image aspect of point and shoot .jpeg shooters. This camera is not a point and shoot, it does require some tweaking and forethought but nothing that can't be easily accomplished and customized to your taste. Basically the majority of negative comments are coming from C...n shooters. It's amazing to me when Nikon stepped up to the plate after being dogged by high ISO C...n shooters they became very critical after a direct hit.
Competition is good and Nikon has answered back.
I like the ability to customize my menus and set up nearly any combination I like and quickly dial it in. Setting a PRE white balance is so simple, push a button, roll the dial, push a button, release the shutter, all on the body, not deep in the menus. If you want bracketing, set it up in a custom menu dial it in, your done. This camera will make you think about what your doing but once your set it's a done deal. Image quality rivals cameras in the 2,000-3,000 range unless your pixel peeping, I can find fault with just about any camera in that price range if I'm pixel peeping. I shoot exclusively in manual and all my images are shot in RAW. It's so easy to get it right in camera with the D300, if I take a bad shot it's my fault, post processing time has gone down and behind the lens time has gone up. Auto focus (51 point) and focus accuracy is wonderful, 3D tracking is just too cool. The pluses definitely out way the minuses, the best advice is to pick one up and compare it with the competition and you'll more than likely want to take it home.