The best of the Hammer Frankensteins, I think, although I’m not a huge fan of the series. (Peter Cushing aside, obviously.)
The central conceit of this one was recycled for the TV movie Frankenstein: The True Story. The film also features a wryly humorous ending, which is as far as I remember never referred to again in the films that follows.
I apologize for the lack of MotDs lately; I’ve been having a lot of Internet issues. It’s working now (Sunday night), so I’m putting this up now and scheduling it for tomorrow morning.