If you are like me and are fascinated by the history of London's pubs, this is a great reference book.
While it doesn't cover a vast number of public houses, the ones it chooses to refer to are justifiably interesting. There's enough meaty history here to make the book good enough as a stand alone read. But if you want to use it as a bible of "good places to drink" it's a worthy addition to your library, too.
I like the way the chapters are arranged around areas of London, so if you feel like an excursion, say to Hampstead and its surrounds, you can create your own pub crawl based on just one chapter of the book.