Is edenpure a efficient electric space heater?

Efficient, yes. But a poor choice for a heater. It's just a marketing gimmick. Every electric heater is nearly 100 percent efficient. Efficiency is a term not understood by many. Energy efficiency - useful work per quantity of energy. In other Words, What is the job of an electric heater? To make heat. How much of the electricity fed to the heater is turned into heat? All of it. That makes it 100 percent efficient. In contrast an incandescent light bulb is only about 5 percent efficient, only 5% of the electricity fed to it is converted to light the other 95% is converted to heat.