Throughout the years he managed to "weather the changes in public taste and the pressures of the Hollywood studio system without compromising his style, his taste, or his ethical standards," as his honorary degree from Loyola University of Chicago is inscribed.
I've seen many of his movies. These are ones I have blog posts on:
A Woman's Face (1941)
Gaslight is at youtube in parts, with the first part here. A Star is Born is available the same way, with part 1 here. Camille begins here.