I think the answer may depend on the student as much as the instructor. All students make mistakes and part of being an instructor is how you respond to those mistakes. "Constructive criticism" seems to be more "robust" in the military and whether the student will respond to that style of teaching depends on the student.
That said, I have found the ex-mil instructors I've had have required a higher standard of me than the civvies and this is, eventually, motivating. They can just take a little getting used to. I've flown with 3 ex-mils and 3 civvy instructors.