In short, the film does correspond to the book as much as possible, and that is a plus.
When talking about Mary Shelley's novel, we should bear in mind that it was created in the first half of the nineteenth century, when the cinema was not even in its infancy and books were the most popular form of art. Consequently, readers had to turn on their imaginations more often than they do nowadays, and even though Mary omits details of the monster's creation, audiences read such stories instantly and with pleasure. These days, of course, this is considered an omission, and since the purpose of any movie is precisely to visualize what happens, we are faced with a unique case where any adaptation is bound by default to be more interesting than the source material.
Kenneth Branagh, the man I personally associate with the author's voice in Walking with Dinosaurs, not only directed the film, but also played the lead role. Yes, yes, it is Branagh who plays the role of Frankenstein himself, and perfectly, I must say! Trying to be in line with the worldview peculiar to Europeans at the dawn of 18th century, the actor shows a sentimental, but decisive man who makes a discovery, faces the consequences and, in general, vividly demonstrates the eternal rule of every case: the first pancake is always a slam dunk. In science, especially medicine, it is especially important to restrain emotions and not to overreact to failures.
To the idea of the creation of life, the filmmaker adapts medieval studies of both Europe and China. Of course, it is impossible to pull this off in reality, but what can you do for the sake of a beautiful science fiction? By the way, the creator is played by Robert De Niro - an unexpected choice, right? And curiously, the film emphasizes tragedy rather than horror - exactly as it was in the book. After all, the novel, contrary to popular belief, is no horror at all. In this adaptation, Frankenstein's creature is perceived not as a monster, but as a cripple. A very menacing, but unhappy cripple, who just did not like his father as a product of the experiment. Helena Bonham Carter has one more significant role - with her activity the actress comes to the foreground and attracts as much attention as Frankenstein and his creation. In one key scene, the actress appears in such terrifying makeup that the question of the creepiest character becomes moot...
Admittedly, I don't understand what "lost" script Frank Darabont was outraged about, if the book is, in fact, the script. Following the source material, this film is just as tragic, just as doomed, fantastic, and in some places naïve. The writer's legacy lives on and thrives.