The technology can be seen in the illustration that Fornetto (Garth) uses:http://www.fornetto.com/tech-info/fornetto.html
The naked flame never enters the cooking chamber and so in this sense it is quite 'idiot' proof. I considered getting this one which is similar and to me prettier than the Koala oven. I may still get one because you can smoke meat in it and it is convenient for other types of WFO cooking. It retails for about 900 AUD, the cheapest in the Koala range is about 1200 AUD. It cooks a nice pizza, but if you are after VPN pizza I don't know if this will do it. The thermometer on the contraption tops out at 400 deg C (about 750 deg F) , about 80-85 degrees less than VPN heat (485 deg C is about 900 deg F). Will it reach higher heat? Fairly certain you can if you spike the firebox but with the deflection built in, it's hard to say how much of that will reach the cooking chamber unless one tries it. Then again , you'd be operating it in temps the manufacturer does not recommend.
Here is the Garth:http://www.gartheurope.com/garden-oven.html
...same technology within. The Thermometer on the Garth model goes higher though in their manual it also says safe operation limit is 350 deg C, as it does in the Fornetto. All these ovens seem to recommend 300-350 deg C as pizza cooking temp (i.e 570 - 660 deg F). If that is what how you want to cook your pizzas it's great, and it is clear where the target market of these ovens are, they sit in that grade above the domestic kitchen oven but below a proper WFO. They are quick, clean and a real conversation piece in your back yard though.