It's safe enough, in the Finnish army we occasionally get the tent heater red hot, and as long as nothing flammable touches it or is too close, it's fine. It will radiate heat quite well when that hot, but won't be anywhere close to dangerous if you know what you're doing. In the tent we of course have some water nearby to extinguish the possible flames but still.
You basically need to have it glowing red if you're to keep the tent warm in -15 °C or lower. - 30°C needs something closely resembling the picture posted.
You make it red hot because you don't want to crawl constantly back into the tent. And you never, ever want the fire to go out, because of all the shit you'd get for it. Mansikka for life
Looks quite efficient. See also: rocket stoves, specifically the pocket rocket design. Though the ones with lots of thermal mass probably serve folks better while taking up more space. Various wood gasifier stoves are pretty neat. I've got a little one for camping.
In this instance, I'd predict the components of this stove will oxidize away quickly.
It is all stainless steel. So it will be able to last.
I once combined a steel can wood gasifier with an aluminum alcohol stove using an ethanol and peroxide fuel that could boil 500ml of water in under 6 minutes with an ounce of fuel and burned violet. Not ideal for lightweight camping, as I intended, but man was it efficient.
And then one day you are there working on something at the vise, you drop something, and then you need a full back graft, and now you have weird hairs growing in your shoulders.