Clostermann's own book is pretty illuminating, even without the testimony of those who flew with him.
Yet in his later years he could be charming and modest - to a fault.
I suspect that history will view him as a very flawed genius, whose own arrogance and over-inflated claims can't dent the fact that while he didn't win the war single-handed, as he seemed to think, he did play an important part in one part of it.
I don't know whether his anti-English prejudices will allow people here to view him dispassionately.