I`ve ask the owner and here is his answer
it works very well, but I would change something: as you can see, the barrel is completely hidden in the stove, as opposed to these rocket stoves where part of the barrel is exposed.
The consequence is that my rocket stove
has a lot of inertness and thermal mass (stays hot very long after the fire has been extinguished), but there’s not much direct radiant heating. And it would be nice
to have a bit more of that.