This version of the story has several changes that make it different from the original. First, Dr Mortimer and Lord Charles are both portrayed as sinister characters. This is a significant change from the original where they are portrayed as good guys. The second change is that Alice Brandt's role has been expanded to include her in more important parts of the story. This is a change from the original where she only plays a supporting role.
The third change is that the movie is set in a moody and atmospheric way, which makes it more interesting to watch. This is a change from the original where the movie was set in a more light-hearted manner. The fourth change is that the movie is photographed in a noirish style, which adds to the atmosphere of the movie. This is a change from the original where the movie was photographed in a more bright and cheerful style.
Despite these changes, many fans may find this version somewhat disappointing. One reason for this is that the character of Sherlock Holmes is played by Fritz Rasp, who is not as charismatic as Conan Doyle's portrayal. Another reason is that the title hound does not play a big role in the story, which is a downgrade compared to the original.
Overall, while there are some changes made to the story, it seems that the most significant change is the expansion of Alice Brandt's role and the addition of Dr Mortimer and Lord Charles as sinister characters.