While "The Fiendish Plot of Dr. Fu Manchu" is by no means the best of Peter Sellers' work, for those who are fans and appreciate his whole output, the movie is enjoyable. Multiple characters for Sellers, "Goon Show"-type humor, a measure of unreality and strong supporting performances all contribute to it. The movie manages to mix only a few out-and-out laughs with some more subtle comedy, some farce, and even a few moments to ponder. The fact that it was Sellers' last performance might add to its attachment for fans, but I'll argue that it is a good and under-appreciated comedy. I'll hang onto my VHS copy and hope that a DVD version is produced.
