Vincent Price is wonderful in the challenging role of Phibes. He doesn't speak a single word in the entire film except for voiceovers. He makes it work in a way that only he can. I think it's one of the strongest and most interesting performances of his career. Robert Quarry is also excellent as Darrus Biederback who, like Phibes, is also eager to find the River of Life.
The cinematography and sets in Dr Phibes are delightful and imaginative. Bright colors abound, especially in the scenes where Price and his nemesis Biederbeck are involved. Set pieces have bold, geometric lines and are a feast for the eyes. These scenes are in sharp contrast to those that happen at Scotland Yard, where the colors become more monochromatic and the set pieces are plain and ordinary. Exceptional work as far as I'm concerned.
Although the story is as old as time, somehow it feels fresh here. This is an unusual horror film that only the late 60's and early 70's could produce. I've never considered this time period to be a strong era for horror but this one really stands out for me. Dr Phibes is the sequel to The Abominable Dr Phibes (1971). I must confess that I haven't seen the original but it's now on my Netflix list since it can't be watched instantly.
Once I see that one I can do a comparison of the two. So for now, Dr Phibes Rises Again is a fine film on its own. [If you're a fan of the original Star wars, keep your eyes peeled for a cameo appearance by Peter Cushing who also did The Curse of Frankenstein (1957) and Horror of Dracula (1958) and many others.]
For more info check out the film's entry in IMDB.