<light spoilers>
Early science fiction! The book is much better when you understand the historical context in which it is written.   Otherwise it can seem a bit….goofy..

Victorian paranoia around scientific advancement  and particularly vivisection put the horror element into context.  

The mystery of what the island is becomes relatively apparently early in the book.  

It’s a short read but also fun to listen to on audiobook.   good to read if you are interested in the development of the horror genre / science fiction and  how monsters are a reflection of societies paranoia. 

Wow. I did not expect this book to be so brutal.

Something that everyone, including every adaptation, gets wrong is that they think he's combining humans and animals. He's not. He's vivisecting animals and surgically deforming their bodies to look more human, believing that if they look at least humanoid they'll suddenly 'become' human. They're just innocent animals living in horrific pain and existential terror. None of this is their fault.

The parallels with colonial racism are obvious, and the metaphor here is so ugly I'm not going to touch it with a ten foot pole, not here at least.

The narrator, Edward Prendrck, is... well, he's evil. Horribly, painfully evil. He's borderline more evil that Moreau himself. Reading the book is made all the more difficult because we're having to listen to his burning hatred for everyone around him, especially the animals. He H A T E S the animals, only because they look weird. He actually uses the word 'hate' on practically every page. Knowing that this is a metaphor for colonialism, this paints a reeeally bad light on our protag here. The part that gave me pause was when he and Montgomery commit a genocide. Here's how he describes it:

"Then we went into the laboratory and put an end to all we found living there."

That's it. They shoot up what is essentially the animal (occupied nations) version of Unit 731 and that's all we get about it. No remorse. No sadness. No Guilt. NO EMPATHY. It never even comes up again.
Absolutely brutal.

Extremely disturbing book. That's not a compliment.

Unsettling meditation on the relationships between humanity, nature, and science