Jaxson: Also, the 3 times better than a standard electrical heater is only relevant during the optimum operating conditions, namely when your desired internal set point is very close to the ambient temperature outside.
ie You would expect 300% efficiency during periods where it's 20 degrees C outside and you want the room to be 21 degrees inside. The efficiency drops as the differential temperature gap increases. Simply, it won't be 300% efficient when it's 1 degree outside and you still want the temperature inside to be 21 degrees.
Flued Gas heaters are roughly 80% efficient at all times and temperatures. Gas costs roughly 1/3rd the cost of electricity so can work out cheaper during cold periods where the heat pump is not operating as efficiently.
Gas heaters don't cool so well though. Heat pumps can dehumidify, but only in cooling modes, which you don't tend to use so much when it's cold.
Pros and cons to everything.
+1 and modern wood burners are pretty efficient as well, as long as you have a ready (and sustainable) supply of wood.