Field expedient (which is fancy speak for improvised) stoves have been around for a long time. They are basically a means of concentrating the heat. They have both advantages and disadvantages. Disadvantages are: a)Take time and require tools to construct. b) Need level ground. c) Can melt if the fire gets too hot.
Advantages are: a) Require comparitivly little fuel. b) Easy to control. c) Work in poor weather (i.e. wet & windy) conditions. All things considered, their advantages outstrip the disadvantages by a very long way.
One tip: if possible, cut a slot in the bottom of the can to feed the fuel into.