Not one of Hitchcock's best. I love his movies and style. But Marnie was weak. Like To Catch a Thief. Perhaps he was more concerned about the beautiful actress than the plot. Sean Connery's performance was up the par but Tippi Hedren performance was flat and dull. She played as cold as a fish and when she was in psychotic trance an amature could have played the part better.
The plot was not believable either. Like when she tries to kill herself face down in the pool and miraculously Mark could find her in that big ship/cruise and save her in time. Or by miracle Mark,a successful businessman becomes a good psychiatrist by reading just one book on the ship and unravel her deep childhood trauma.
There was no suspencful climax in the movie to keep you at the edge of your seat and the romance was one sided and dull.
It's funny when you can detect the excess use of the green screen.
I hope I didn't spoil the movie too much.