It wasn't exactly groundbreaking at the time either, but the power of the characters have managed to elevate it above similar (though, IMHO, inferior novels) which were published in the era.
I'm completely guessing here (not having any contemporary reviews to hand), but the notion that Dracula was, at some point, revolutionary is possibly erronious. The format of the novel is a staple of Victorian prose, the supernatural nature of the threat isn't unique, and most of the vampire lore that the story "introduces" has some basis in European lore anyway. None of that matters, because the imagery is strong enough to rise above any possible criticisms which could possibly be laid at the text.
Slightly outside the remit of this thread, but I'll add the following anyway... When Nosferatu was released (1922) there was the distinct tinge of familiarity to Stoker's novel. So much so that it was the subject of legal intervention, and the film was threatened with complete destruction. It is interesting to note that the most effective appearance of vampirism on film was directly influenced by Stoker. Ignore the film adaptations from a strictly adaptive point of view - none come close to the story, even Coppolla's attempt.