As Chowhound ipsedixit sees it, dark roast coffee has taken over the world. She prefers a light roast that doesn't destroy the nuances of high-quality beans, without having the life scorched out of them. Maybe overroasting is a way to mask poor-quality coffee, just as overoaking is a strategy for masking low-quality wine?
Agreed, says Jerseygirl111, who prefers to taste the essence of the coffee beans she's buying, not charcoal. Dark roasting brings out a coffee's bitter flavors. For those who drink it black (Cheese Boy, for instance) a light roast delivers a purer coffee experience.
But it's not as simple as dark is bad, light is good. Chowhound mcf thinks the beans themselves should determine the roast—some single-origin beans and blends are at their best roasted lightly, others medium, and still others dark, depending on their inherent flavor.
And it's possible to roast too light. Roasting less preserves a coffee's acidity, which is why light-roast aficionados tend to prefer bright, acidic, and fruity flavors. But an overly gentle roast can yield coffee that's just too acidic, grampart notes. The difference between your perfect roast and under- or overroasted coffee is most likely just a few seconds more or less in the roaster, from the "second crack" that chileheadmike likes, to the burned-tasting beans with an oily sheen that grampart detests.
The way to great coffee, then, might not be through adherence to a single roasting style, but by finding a roaster who sources great beans and has the skill to bring out the best in each batch.
Top photo: perusing the coffee menu at Sightglass in San Francisco by Flickr member Citoyen du Monde Inc under Creative Commons. Above: the pour-over station at Four Barrel Coffee in San Francisco by Flickr member Robert Raines under Creative Commons.