Very cool. I also built a drone with only one motor and only one rotor, it took about three months and I learned more about drone firmware than I ever wanted to. I can't fly it but one of my sons is an absolute genius with this kind of thing and he can make it do tricks.
This kind of project is extremely rewarding. What's interesting here is how many things we did different. I used four servos and vanes in the airstream so that the whole thing would be mechanically as simple as possible, which makes this solution even more impressive to me (though I think mine is a lot more stable in flight judging by the video).
I think I went through 10 prototypes before the first one actually flew and #13 flies very well.