Probably a good thing everybody doesn't do it, though.
Fireplaces throw off a LOT of pollution. If, as I gather, you live out in the sticks somewhere, it's not a real issue, but there are cities that get actual smog on fireplace nights.
Modern gas-burning fireplaces don't pollute, and are almost as realistic as a real fire, but it goes without saying that this isn't the most efficient way to burn gas for heat.