Excellent.- It's one of the rare horror movies that has actually
'exaggerated on a true theme' I.e. The horrific WW2, Nazi medical Doctors were using prisoners as a way of experimenting on, so as to achieve future benefits to the their own armed servicemen and
citizens alike.
What is also an unfortunate similarity with the fiction of the film to fact, that overall, Nazi scientists were far more advanced than their Allied counterparts.
As a technical comment, all the opening 'flight scenes' were very impressive.