I found this book incredibly disturbing. Wells was influenced by the time he spent studying with T. H. Huxley, and it is perfectly obvious from what Dr Moreau is trying to do that Darwin was very much on his mind. The story is plausible at many levels, particularly regarding the experiments with animals.
Moreau never becomes a real person, yet represents the torturer we all dread. His experiments become scary from the moment we share the puma's pain, simply through its moans and groans.
I found the character of Montgomery much more real, somewhat reminiscent of the part played by Humphrey Bogart in The African Queen. There is no malice in this man, but no sense that he will protect Prendick either.
I was relieved towards the end, though I won't disclose any details to avoid providing any spoilers.
The novel is extremely well written and suspenseful throughout. I found it entirely relevant and contemporary, despite having been written at the end of the nineteenth century and being only Wells' second novel. His descriptions are particularly vivid and haunting.