I have the species plant, not the cultivar 'Flying Dragon'.
I have 3 trees that are 15 feet tall or so, and this year produced about 6 five-gallon buckets full of mini-oranges!
Yes, they are edible.
We made kind of a lemonade out of them one year.
It tasted kind of like lemon and kind of like grapefruit.
The only problem is the peels are kind of gummy and make your knife and cutting board VERY difficult to clean.
I love these trees, and get many compliments on them. The foliage is beautiful, and they look pretty amazing covered with oranges way up in Virginia!
http://davesgarden.com/guides/pf/go/31545/