I think it might have some elements of a McDojo, but I cannot confirm this. The reason I bring this up is with some anecdotal comments made by my cousin. She was taking two of her sons to USSD classes in Orange County, California and commented that the classes were getting too expensive.
If I remember correctly, she was stating that to go up another level or learn more kata/forms, they had to pay more money, meaning substantially more. That the tests kept getting a lot more expensive and I beleive there was something to do with a contract, as well. But I am not 100% sure of this.
To have a pretext where much more money is required for advancement and continued study has always been a bad sign for me. However, this does not invalidate the instruction or the instructors.
I have no personal experience about USSD outside of this. Just remember the comments and thought they were McDojoish.