Some people say the pace of this film is a little slow, but how is this different from any other Hitchcock movie? They all move very deliberately and, as a point, have spurts of suspense and brilliant montages injected through it. This movie gives us just the right amount of comic relief which make the suspense scenes seem all the more suspenseful. The Albert Hall scene is one of the best examples of Pure Cinema that exists in Hitchcock's collection (the best probably being almost all of "Rear Window"). Pure Cinema for Hitchcock meant a series of usually small pieces of film fit together without dialogue, in order to tell the story visually. This is, of course the basic definition of the Albert Hall sequence, as well as the shorter staircase sequence at the end of the picture.
Not many slip-ups by Hitchcock here, and the acting is superb especially by Doris Day in a rather surprising serious role.