As films go, this was rather enjoyable if you watch films, like I do, with the intention of berating every aspect of them to your entirely uninterested cats. It was suitably poorly script and in some places frankly ridiculously over the top (which led to some very fun comments and general viewing pleasure).
However as an adaptation, it was terrible; bearing little relation to the book in themes and keeping only really major plot points. It also did the infuriating thing of looking like it would follow the original storyline before veering off in an entirely new direction to create unnecessary drama and tension. It was not only unfaithful to the book, but also seemed to betray some of the key messages and feelings explored in the book (particularly Victor's feelings towards his creation and a proposed second creation).
In short, if you found yourself thoroughly enjoying the book and are looking for a good adaptation, give up and cry because this will make you want to rip your hair out. (And I have yet to find a genuine faithful adaptation of Frankenstein anyway)