Fireplace is extremely inefficient, and really bad for both your (exhaust fumes get into the room anyway), and your neighbors (the smoke doesn't just dissappear) health, though.
replyI love the heat and smell of a good fire as much as the next guy, I'm just not sure it's worth the risk of cancer and respiratory diseases.
If efficiency is important, like if you are using wood for primary heat, you should at a minimum be using a sealed box stove which should be pretty efficient and have little to no smoke escaping.
replyAlternatly you could just use an outdoor stove that merely heat exchanges to the inside.