When one has seen the Shakespearean treatment of this story, it falls far short of the masterwork. That said, it isn't fair to compare a low budget period movie to Shakespeare. I think what I did like about it, though, is its visuality. I liked Karloff going through a day's work, putting one more weight on a guy they're suffocating, like a cook checking to see if there's enough salt in the soup. I really like Basil Rathbone. Of course the Sherlock Holmes movies are my favorites, but he is a consummate actor and rises above everyone else in the story. I was disappointed in the lack of character development other than Richard and the silly romantic subplot.
Karloff ,also, should have had his moment to confront Richard since he is a fictionalization anyway.
It was neat seeing Vincent Price begin his mugging, whining characterization of the ineffectual son of the king. I did like the drinking scene but wonder why no one else was there to observe the result. Richard (Rathbone) seemed to have an awfully easy row to hoe. I was also disappointed in the big battle scene at the end, but won't spoil it here.
All in all, I liked looking at this movie, but felt sort of empty at the conclusion. Also, where does it come off as a horror movie, other than the rather comical dungeon scenes?