Even for a classic, "Dracula" is an exceptional book in many ways. Since published first in 1897 (due to the content it was sorted into the 'pornographic' section of the market - what can I say? vampire brides are loose women...), the novel has never been out of print - and it has been translated into almost every major language still spoken on earth.
To be honest, the book isn't as 'hot' as most of the movies based on it. There's pages and pages written in the style of various diaries, excepts from newspapers and stuff like that. It's a good read, if you like that sort of thing (as I do), but it's not a fast read ... or easy to understand. It's quite thick, too.
But what Stoker has understood on a very basic level, just like Polidori when he wrote "The Vampyre" or Sheridan LeFanu when he wrote "Carmilla", is that the vampire is a very sexual creature - even without vampires having sex themselves. The werewolf is a savage creature, the ghost usually can't interact with people on a physical level and we all don't want to imagine Frankenstein's creature on a date, but the vampire hunts - and kills - by seducing. This has made "Dracula", whether you read it or watch a movie (I'd suggest the Francis Ford Coppola version - or the one made by Hammer, although it's not exactly close to the novel), one of the longest-lasting stories in the media. Count Dracula himself does not just jump out of the dark, grab a person and drain it (although he probably could...), he seduces, drinks from his prey during various meetings until the final moment of the kill (or the change of a mortal into a vampire). The same thing is true for Polidori's Lord Ruthven or LeFanu's Carmilla. And if you look to modern vampire stories like those of Ann Rice, it's even more obvious.
But Stoker, although not a full-time writer, wrote more than just one novel. In addition to "Dracula", he wrote three more novels (although I have to admit that I never managed to read through one of them) and a host of short stories. The short stories are actually better than the novels - a fact also true for Arthur Conan Doyle, but that's another topic. Especially those gathered in "Dracula's Guest" surely are worth reading. Stoker wrote rather dreadful stuff, especially when he was not using pages over pages for it.
But this is about the other novels (which have also been converted into movies). There are two I can recommend to those who have managed Dracula (as they are rather similar in style). Those are "Lair of the White Worm" and "The Jewel of Seven Stars".
"Lair of the White Worm" has only been transformed into a movie once (and said movie features Hugh Grant in a kilt - a good reason to watch it on it's own). The basic story is that of a priestess serving an old god (said White Worm, which is rather a dragon without legs or some sort of dinosaur than a worm in the way most people would understand it today). The priestess wants a young (and, naturally, innocent) girl as the next sacrifice for her god ... and a host of heroes (men, but in Stoker's time that went without saying) are fighting the serpent-like woman and her god. You might hazard a guess on the outcome, but it should be clear what happens in the end...
"Jewel of the Seven Stars" has been used for a movie at least twice. There's "The Awakening" with Charleston Heston and Stephanie Zimbalist and "Bram Stoker's The Mummy" (produced not so long after "Bram Stoker's Dracula"). The latter is more true to the original story, although both have been taken from their original setting (Stoker's own time) and 'replanted' in modern times. It doesn't really harm the story though, unlike "Dracula" and "Lair of the White Worm" it hardly works with specific means. And an ancient Egyptian queen (one of the evil sort, of course) coming back to life in an archaeologist's daughter isn't bound to a special period of time. And it's not ending too well...
In both cases the movies are actually better than the novels, at least for a modern reader. Stoker's style isn't easy to cope with and he definitely wrote better prose in "Dracula" than in his later novels. Maybe it's because essentially (though with female villains) he's been rewriting "Dracula" in the other stories. It's always basically the same. There's a threat coming from outside (so the more or less reluctant 'heroes' are not really to blame themselves). There's a band of heroes that forms, there's the damsel in distress and finally there's the demise - which way ever - of the evil (though not in the movie versions of "The Jewel of Seven Stars", in which the queen survives).
But nevertheless, only very few people know about Stoker's work, as long as it's not "Dracula". And that's a shame.