Can anyone say anything about the disadvantages of traditional rural cookstoves?

Most of the rural cookstoves are of masonry construction and are often built without much care. So that the combustion of various fuels in use is not sufficient. Release a lot of smoke. Will pollute the environment, but also a lot of heat loss for nothing. To improve the biggest feature of this traditional stove is easy to build. Now the rural areas are advocating the use of biogas lighting and heating, the use of the stove is less than the original.