Shamefully, I've never heard of that film, but speaking of Cotten, I watched Welles' The Magnificent Ambersons for the second time a fortnight ago, and was mightily impressed, by the general production, by Cotten's performance in particular.
I've seen him in that film, Citizen Kane, and Hitchcock's Shadow of a Doubt, and he's been excellent in all three.
Other than those titles you mentioned above I've only seen Cotten in one other movie - "Gaslight", and I'd highly recommend that (with Charles Boyer, Ingrid Bergman).
BTW - This "Love Letters" takes place in England. Reminds me a little of "Rebecca" and "The Uninvited" with its country home and train rides into London. I probably would not have ever heard of it either, except for the good luck of having Turner Classic Movies (TCM), a cable network which airs mostly 1940's/50's classics.
