This is just a really, really fun book. This isn't clear for the first few pages, which are, for some reason, the weakest part of the book, but once it gets going it's pretty amazing, funny, imaginative, clever. It's also intriguing, in that it delves deeply into the past but tells you very little about the present (there are apparently other related books, so perhaps one of them explains the modern world).

While it's not crucial, I'd say it's worth reading 3 Men in a Boat first just so you can catch a few clever references. Also you should read it because it's a really good book.

But you won't really miss anything if you skip that. The important thing is, you should read this book, because it's just really, really fun.