After having shot with Canon's for years, more recently the 5D, it just seemed that Nikon had been making better advancements. The D300 is a perfect case in point.
I shoot predominately nature and landscapes and this camera is an absolute pleasure to work with. The direct view, along with the exposure lock, is perfect for split neutral density filter work. Additionally, I have yet to have to photoshop out any dust spots - I mean none.
Understanding the menu options has resulted in a two stage mirror lockup with a second touch of the shutter release to obtain a 1 second timer. Convenient especially since the mirror lockup is not buried in the menu.
Possibly the biggest plus of the D300 is the minimal post production needed. It just seem like I had to struggle with the 5D RAWs - not so the D300 - minor white balance adjustments (although the auto consistently does an excellent job) and sharpening - that's it. This is the camera for photographers who want to photograph and not become a photoshop slave. Now post production is available to enhance an already photogenic image.