The world-building has many merits: I loved the modern need for a fortress of London, and the prosaic interferences of the zombies with the delivery of the post. That said, the society did not seem sustainable: the post was intercepted a little too frequently for it to seem a credible system of communication. What logic was there to society in a married woman giving up her martial arts? The plot too had strangely unresolved secondary elements. In particular, the argument of Japanese vs. Chinese martial arts was not carried to much of a conclusion.
If you are a P&P completist, if you are keen on zombie books, or if you would never bother reading Pride and Prejudice unless it had zombies in it, the book's worthwhile. Otherwise? I don't think I'd bother.