I first saw this movie on t.v. almost 20 years ago as Assignment Terror, and was excited when it first came out on video. Unfortunately, the video cut about 9 minutes of total running time from the film, retitled it as Dracula Vs. Frankenstein and left it as a jumbled, incoherent mess. Most fans will also be confused because Dracula and the Monster never fight in the entire film.
I'm not saying this was a great film to begin with, but some of the editing complaints seen in earlier reviews come from the video version, not the original release. In its original form it was a strange yet fun action/horror movie in Paul Naschy's Werewolf Waldemar series. Naschy also plays the Vampire (Count de Mierhoff), Mummy (Tao-Tet) and Franksollen monster whenever possible.
Michael Rennie is one highlight, and gives his best possible attempt at making a profound statement in his last speech in the film. I'm surprised they even left that in, since most of what they took out was the plot. Apparently the video production figured no one pays attention to plot in a movie like this anyway. And yes, that's the same Karin Dor who appeared in Hitchcock's Topaz in the same year.
Hopefully, when this comes out on DVD they'll get it right.