This was a pretty awesome hammer gothic horror film. I may even dare to say that better than their Frankenstein and Dracula series.
Peter Cushing is amazing in his role as always, doing the scientist. But I take my hat off for Christopher Lee. A great performance, although he doesn't really appear until the third act (and yet is the top billed cast).
The rest is perfect. Good acting, awesome atmosphere, and a compelling story makes a great view.