I believe the ending in Suspicion should have been different, it's based on a book where Cary Grant's character was a murderer. I could see why someone might not like Suspicion. Cary Grant is a little too brash and Joan Fontaine a little too unsure of herself.
I did see Suspicion in the theater as well, and I was regretting having eaten all my popcorn and not saving any to throw at the screen. That ending sucks. Big time.