Frickin' awesome! Make it sweat!
In order for a sauna to have therapeutic value, it needs to get really hot. So for this sauna there is a little insulation required. Once the ceiling is insulated and sealed, and weather striping is applied to the entry, it's much better. The ceiling panel on mine didn't sit flush with the frame because the wood is a little warped. I could see through a gap into the room. Needless to say, the heat escaped easily. Insulating the ceiling panel is easy however. The protective Styrofoam boards that the sauna is packed with are perfect for this. So don't break or toss them. Simply cut them to size and drop them into the ceiling panel and then close with the provided board. Why this isn't done at the factory is beyond me. This sauna also loses heat through the pretty glass panels and the door. It's not by accident that commercial saunas have thick insulated doors :) All in all though, it's a very good looking sauna and I'm very happy with it. A suggestion I have for the manufacturer is to give the customer a choice of heaters. That way one could chose a stronger unit for the 3 person sauna. As is, it's the same unit that comes with the smaller 2 person sauna which I assume gets much hotter. Anyways, don't let the lack of insulation deter you from buying this unit, it's a super easy, quick and inexpensive fix.
My only regret was not purchasing sooner. I have always wanted my own sauna after spending too many hours at my local gym. Heats up daily to 175F or more within 5-10 minutes of starting. Comes with all the basic of a traditional sauna and pretty easy to install and assemble.