I had a Yukon Big Jack, which is the same furnace except the Super Jack has a secondary heat exchanger that the BJ does not. Like was previously mentioned, they are very well built, great warranty, Etc. My experience with their customer service has been good.
Not the cleanest burning units, they claim to have secondary burn, but what I found was that it only happens during high burn (combustion blower on) and even then only right after a fresh load of wood. I had to clean my chimney quite a lot. Ultimately I switched it out for a Yukon Husky Multi fuel furnace for a variety of different reasons. I'd give the BJ 5 out of 10, I guess I didn't hate the BJ, cuz it is in service at my sisters house now. She has had better luck with it than I did, but they burn slab wood and it is chewin through a PILE of wood!
If I had it to do over again I'd look at PSG Caddy, Drolet Tundra/Heatmax (is having some first year model hiccups, but still worth a look, especially for next year) and if ya wanna do it really right, check out the Kuuma Vaporfire. Stihlydan has one, I believe he is more than happy with it.