Several people have mentioned the music from this film, and for good reason. This was one of a handful of extraordinary scores by the largely forgotten Michel Legrand (THREE MUSKATEER 1974; SUMMER OF '42, BRIAN'S SONG, among others), and is one of my favorite twenty or so film scores ever. This movie, well-photographed as it was, simply reeks of Gothic atmosphere in great part because of this music. Passionate, sensual, beautiful, and tremendously dramatic, it was even released as a record album in 1970 by the short-lived American International Records Label and, unfortunately, has never been made available on CD. It would be worth a purchase on eBay! I also feel that, while Dalton as Heathcliff is by no means in the same acting league as Sir Laurence Olivier, his passion for Calder-Marshall (who is less effective as Cathy than was Merle Oberon) is nonetheless more urgent and less studied than Oliver's was in the '39 version.
I enjoy the original film for its moody black and white imagery and its fine romantic score (by Alfred Newman, also not available on CD); but, though it's admittedly a lesser film, by a small margin I prefer this 1970 take which, without Legrand's evocative scoring, would probably have been a bust.