About 80% efficient is the norm for our decent stoves, although since they all use secondary burn and are made so they simply can't be shut down to smolder they all roar and eat wood. They throw heat, burn clean, but eat wood. The very best stove I've seen is a make called Burley, 89% efficient!
Aha, I've found out that efficiency is measured differently here. 60% here equals 76% euro. I didn't think our norseman was that bad and it has a secondary burn system as well. Since the long flue goes straight up through the top level (our bedroom) and you can feel heat radiating off it, it may be a bit more effective than nameplate too.