Which settings?
The advantage of the D300 over the D80/D90 are the
dedicated buttons on the body to change settings rather than having 2 buttons perform the same task (e.g. ISO). Most of the settings you can change on the body of a D300 can be changed on a D90 just as easily. However, from a design standpoint, the D300's controls are a definite advantage.
The one thing I wish is that the ISO button on my D300 was moved to the left of the LCD, or that a duplicate button was placed there. When you're ready to shoot, and are holding the camera properly, it's easier to press the ISO button on top without moving your left hand a lot and taking your eyes off the viewfinder or letting go of your lens with your left hand. On a D70/D70s/D50/D80/D40/D60/D90, you just pull your hand back and hit it with your thumb. On a D300/D700/D3/D3x, you pull your hand back and rotate it a bit to press the ISO button with your index finger.
Otherwise, the D300's controls are better, although I don't know if the number of settings that can be changed on a D300 is all that different than on a D90.
It is worth it to me. Someone posted this on dpreview and I will post it here.
Quote from Digital Review, D90 and D300 comparison:
-The Nikon D90 offers 12-bit image processing compared to the Nikon D300 were 12-bit or 14-bit can be selected; internal full 16-bit.
-Nikon D90 Body is made of polycarbonate versus the Nikon D300 which is made of rugged magnesium alloy and features enhanced weather seal protection.
-The D300 provides faster start up (0.13 sec) and minimal shutter lag (45ms) compared to the D90 (0.15 sec start up and 65ms shutter lag).
-The D300 offers phase-difference detection Auto Focus in "Tripod shooting mode" (not available on D90).
-The D90 incorporates a 420-pixel RGB sensor for metering compared to the Nikon D300 with a higher end 1,005-pixel RGB sensor. Leveraging the data provided by the1,005-pixel RGB Matrix Meter, the Scene Recognition System in the Nikon D300 provides more precise subject identification, optimizing autofocus, exposure and white balance detection.
-D300 offers both a CPU and AI exposure meter coupling to support metering with older type Nikkor lenses.
-The Nikon D90 features 11 focus points versus the Nikon D300 with a broader AF coverage with 51 focus points.
-The Nikon D300 uses a faster AF module (CAM 3500DX) and offers 15 cross type sensors, Fine AF adjustment is possible on the D300 to match the lens in use.
-Viewfinder frame coverage of approx.96% with the D90 compared to 100% coverage with the Nikon D300.
-The D90 offers Continuous shooting at approx. 4.5 fps versus approx. 6 fps with the D300. The D300 can shoot at up to 8fps with the optional MB-D10 vertical battery grip accessory.
-The D300 offers a greater degree of customization total of 48 custom settings.
That being said I like the additional options/benefits/settings or whatever you want to call it of the D300. It is my choice and I have made it. It does have more settings as I said. Now we can argue what the definition of setting is, but in my opinion the D300 is worth the additional money.
To those that keep repeating it is the same sensor. It isn't the same. Like someone said in another thread, it is "urban myth."