The primary difference between cooking in a small microwave oven as opposed to a larger one has to do with the room available to accommodate dishes. A microwave with fewer than 0.9 cubic feet makes it difficult to incorporate a standard dinner-sized plate.
The size of a consumer's microwave has more to do with available space and purposes for cooking than anything else. Someone living in an apartment who primarily uses the microwave to heat up frozen dinners or dinner plates with leftovers can do just about everything he wants with a microwave at 0.9 cubic feet or a bit larger. People who live in apartments or mobile homes or who are looking for a microwave for the galley of their boat are particularly fond of this size, but with the right wattage, a microwave at this size can work in any kitchen.
People who use microwaves to complete cooking in larger serving dishes are likely to look at a microwave between 1.5 and 2.0 cubic feet. Serving platters containing recently cooked food can slide inside this size microwave for a quick heating, saving the cook the task of plating before reheating.
When choosing a microwave, wattage and durability are also important characteristics. More wattage means greater cooking power, and higher durability means more meals prepared before the time for a new microwave.