Well, a Science Fiction classic if anything is, and yet I had not considered reading it (shameful I know) until I encountered it as course material a year and a half ago. I even thought I had an idea about the story - Doctor builds monster, electricity, fetch-me-another-brain-Igor, monster escapes, farmers with pitchforks and so on. But no. That is a bleak caricature of the true narrative, a ghost haunting popular culture.
The story of Frankenstein is both more grand and sad, and I won't spoil it for you. It is a very good read, and in a way a book that really drove home the idea of the Romantic style for me; Frankenstein rows over a stormy Lake Geneva, he stumbles in the high alps, and so on. Nature standing in for emotions. It also carries the (for its time, but also for ours) very popular theme of the scientist playing with forces he doesn't really understand. The price of knowledge and all that (subtitle is The Modern Prometheus, after all). But in truth it is not about the knowledge, but about what love makes us do, and what we may sacrifice to set things right. Yes, Frankenstein builds a creature. Monster, I don't know.
It's available for free over at Project Gutenberg so if you have an ebook reader or tablet there's really no excuse not to give it a try.