Definitely. Imagine just trying to change how you sleep if you're a back or side or stomach sleeper. For most people that would be pretty difficult, I think. It seems like this is an even more dramatic change.
Difficult but hardly undoable. My dad didn't get a CPAP until he was in his 70s. Turned him into a believer, even though he had to relearn how to sleep. My father-in-law had to sleep in an easy chair after his bypass surgery, and then relearn how to sleep in a bed after that. So it may be difficult, but people do it all the time especially when it improves their quality of life.
I work in healthcare and see these machines all the time. They seem way less invasive then a giant metal lung and would not be hard to adjust to. I wish I had one for days when I am sick like with a flu they seem like they would make breathing much easier.
I have enough trouble with the face mask that I can appreciate how some people don't really adapt well to it. I can handle the nasal mask, but attempts to use the face have failed every time. They do help with colds, at least, they keep me from being stuffed up at night no matter what happens during the day.