The Long Earth series is a lot of fun, and it's particularly enjoyable to see Pratchett and Baxter's imaginations running a bit wild. The Long War is a worthy successor to the Long Earth, although War is a slightly misnomer - the name (and the cover) evoke an idea of massive airships carpet-bombing stepwise Earths, but in reality it's more a war of ideas than of people.

That said, it's still quite a fun book, and I am very much looking forward to the next one in the series.