Saw this film a while ago and was very suprised at how enjoyable it was still, even allowing for it's age and the now very dated style of film-making. Madeleine Carroll is as superb (and as beautiful) as she always was (anyone who's ever seen the Robert Donat version of The Thirty-Nine steps will know what i mean).
The story of a beautiful WWI spy, working in a Belgian Hospital while spying for the Allies, has echoes of the real-life Edith Cavell, And more recently (on a much lighter note ) Tv's-Blackadder.
So, is it worth seeing, the answer is yes as long as you don't have a problem with very old, black & white films, or obvious backdrops..But then if you don't like these sort of films you would hardly be reading this in the first place..