So, this is the classic Jekyll and Hyde story, with a twist!
The most interesting part for me was the inclusion of true-crime elements: namely killers Burke, and Hare; and the Whitechapel murders - for which the movie showed that Doctor Jekyll was also Jack the Ripper.
Now, this is a Hammer movie, so there is a tiny bit of nudity. I would have liked more, but what little was shown was nice.
The production is what you would expect: great costumes, fine acting, good lighting.
My attention was held the entire time, despite the plot being paper thin. Jekyll is working on an elixir that will extend life, and inadvertently makes a potion that changes him into a female Hyde. I can only imagine how this would be perceived in current year.
Maybe what made the story so strange was that it was not about any Jungian duality of man, since both Jekyll, and Hyde were killers.
Realistically, this is more of a Jack the Ripper story, just with the Jekyll/Hyde story added.
On top of all that, there was a love triangle thrown in. So odd, indeed, there was both too much and too little going on here.
Hammer fans will 100% want to see this. Anyone else? Well, I think a lot of horror fans, especially for the era, would enjoy what could be called a proto-slasher period piece.

Post script: The first shot of the movie was a dead rabbit. So, it almost lost me right away. There is no faster way to piss me off, than to have any harm befall a bunny - whether alive or not. Just a few shots later, the same rabbit is slit down the middle. I would call this explicit, but not graphic. Regardless, I don't like it. I've seen far worse done to living bunnies.
The movie was made in 1971, but rabbits today are still the most exploited animals on the planet: they are bred into existence to be sold as pets, they are hunted for sport, they are tested on for everyday products, they are sold for meat, they are killed for their fur.
Rabbits are sweet, gentle creatures. They are here with us, not for us. Buy cruelty-free. Be vegan.