A cast woodburner is ideal. Wood was our only source of heat at my last house, and we used to sleep with the windows open in the middle of winter.
The downsides are the weight, duct work/chimeny if it is not already there, VERY DIRTY (dust and dirt on your carpet from wood), and often you will need to lay brick to satisfy insurance.
For a quick add-on, a pellet stove is the way to go.