Well, I guess the former grill store owner has to chime in, here. I never sold them, because the demand is pretty low and I had to draw the line on inventory somewhere, but I've cooked on them, and they are indeed impressive.
For the uninitiated, they are a form of charcoal grill based on the Japanese kamado, a ceramic cooking urn with a lid. There are several brands along with the Big Green Egg (named such because that's what they look like when closed and cooking), including Grill Dome, Kamado, and Primo. Some also have gas and/or electric versions.
Essentially, you place a very small amount ofcharcoal coals in the bottom, place the food on the grate near the top, close the lid, and control heat by means of vents. Because they are so well insulated (one model weighs something like 425 pounds), the heat is concentrated, and a lot of cooking can be done with very little fuel. Because the lid is kept closed, moisture and flavor are retained. It's a very neat way to cook. Not cheap, however -- typical models can run from $500 to $1,500 or more.
I'm not aware of anyone who got one who felt they made a mistake, although a little of that might be being unwilling to admit making such an expensive mistake.
