A Bad Box There are a number of box smokers sold in big box stores that are simply worse than less expensive vertical water smokers. This is because they have no insulation, thin metal, and a poor fitting door. Typically gas or electric, this type of box smoker is nothing more than a burner or heating element inside a metal box that you can put meat in with wood chips held over the heat to smolder. A little breeze or a light rain and these smokers lose heat. You would do better with the more efficient shape of a round smoker.
A Good Box The better box smokers cost a lot more. Despite this, they produce large amounts of great barbecue in a highly controllable environment and if you need to smoke barbecue for a competition, catering, or a restaurant, these smokers can be the most dependable and easy to use smokers on the market.
Case Study - The FEC-100 I'm not sure if inventor-designer Ed "Fast Eddy" Maurin would appreciate me referring to his competition staple as a box smoker, but look at the picture. The FEC-100 is a stainless steel pellet smoker with an airtight door, heavy insulation, and a computer controlled temperature control system. With the external pellet hopper and the meat probes, you can load this smoker up and not actually open the door until the temperature control systems tells you that the meat is done.
Case Study - Stumps Vertical The Stumps Vertical smoker is, like the other good box smokers, highly insulated. The standout feature on this smoker is the gravity feed charcoal system. Charcoal loaded into the back, feeds down into the combustion chamber allowing for long smoking times. It is the level of oxygen inside the smoker that regulates the charcoal consumption. Simply and brilliant. Stumps smokers, like the FEC are popular with barbecue champions.
Bottom Line If you are serious about barbecue and want to produce a lot of it, then one of these, large, better, and more expensive box smokers. The less expensive versions simply don't have the engineering to be serious about barbecue.