I was surprised how underwhelmed I was, given this movie's rep. The MVPs here are definitely Wyler and Toland who work in tandem to create a visually interesting world.
I suspect the weak links are Hecht and MacArthur, great screenwriters yes but maybe not for this kind of material. (Given his track record, I'm surprised Hecht didn't turn Heathcliff into a reporter.) They haven't just cut out about half the novel, they've compressed what remains, so it feels sudden, particularly with the simmering seesaw of Olivier's emotions.
In sum, what you get are some great moments, but not a wholly immersive movie. IMHO.