I wouldn't expect phenomenal images straight out of the D80 without the user getting familiar with it, but then again I wouldn't expect many of them to be lousy either.
The first thing you should know is that there are 3 different 'metering' modes on your camera.
Spot meter, center weighted, and matrix.
Matrix metering is Nikon's way of trying to get the best image for the lighting conditions. It's a very tough business, and it does some very complicated algorithms to produce the results it does. Having said that though, there are certain lighting conditions that will throw it off, ESPECIALLY when there are huge variations in lighting.
What you have to understand is that, most non-pro DSLR's have a compressed dynamic range compared to what your typical 35mm film will produce. I wonder if it's even more comrpessed then slides, such as velvia. If you up the contrast, this will become even more so.
So, you need to be mindful of the range of lighting you have in the picture.
Lets say you are taking a picture of a landscape in matrix metering mode. Best thing to do is take one test photo and see how the meter is interpreting the picture. Judge
then whether it is underexposed, overexposed, or just right for what you want. Then you can adjust what matrix meter mode gives you by A few F-stops in either direction.
The other metering modes are much easier to predict compared to matrix metering.
In spot meter mode, you are metering off what is in the very center of your viewfinder. It will expose it to get the correct lighting for what a 10%(?) grey subject should be. It is VERY easy to predict what the picture will look like using spot metering just by what you point it to and what color it is, etc. This is very similar to the type of meter you'd find in an older camera.
Center weighted metering mode is in between these two. Good for when your main subject is near the center of the image. Some guessing still takes place though I think.
Again, in all three modes you can adjust the Exposure (called Exposure compensation EV).
Don't expect consistent results until you get familiar with the metering modes of your camera, and which to use when. Also, make a habit of taking a test photo in the lighting conditions first and see what it looks like, and then make your exposure corrections from there. That's the great thing about digital, you can take a test photo and instantly see it, and make any adjustments as needed.
Your camera should have come with a link to the nikon website with video tutorials on selected topics. Take a look at those here:
Nikon Imaging | Global Site | Digitutor
Very basic article, you probably already know this:
Nikon, Inc.
Ken rockwell article. Scroll down to exposure:
Nikon D80 Performance