It really is that good. How much you like this book will depend to a large extent on how much you like the Victorian novel. If you like Dickens, the Brontes, Elliot and the like, then you are in for a real treat, because Thackeray is the best of the lot. Less verbose and rambling than Dickens, less sentimental than Elliot, more ironic than the Brontes, Thackeray is a supreme writer of English - ironic, cheerful and pessimistic by turns, sometimes tender and affectionate then cruel and caustic, he maintains a narrative control that invites the reader to share his moral vision of the hypocrisies and absurdities of Victorian England, and the world we all inhabit.
Vanity Fair has that universal quality of the best fiction - it enables you to see the world in a new way. An hour reading this novel is time spent with a true comedian, someone who sees the grotesque, humorous, admirable, cruel, stubborn, heroic, gentle etc reality of the human condition and can tell it in chapters of the best English since Shakespeare.