I recently read "The Long Earth" by Terry Pratchett and Stephen Baxter. While I thought it was an enjoyable read, I noticed two things in particular about the book as a whole.
1. The Pratchett "voice" seemed to be almost entirely missing. Or perhaps just very, very faint.
2. There were a lot more interesting ideas that were brought up than were followed through on. This is often the case with science fiction, but the nature of this book made this both inevitable and irritating.
It's set in an Earth where there are (potentially) infinite other Earths, a little like the DC Multiverse, and the majority of the population can move from one Earth to another via a process called "stepping." Most individuals require a device called a Stepper to do this. Some individuals can Step unaided. Some individuals can't Step at all. This is where the book seemed to aim for cogent satire, but it was one element among too many other elements for it to tackle this successfully.
The passages that were both the most engaging and the most frustrating were in describing two travelers' journeys through many of these other worlds. There were a lot of very inventive landscapes, flora and fauna introduced and then quickly abandoned as the travelers continued along their journey. There was the notion of being alone in the universe, alone WITH the universe, which turned out to lead nowhere. There were some cute Indiana Jones jokes (seriously) and a robot cat. Lots to like, but nothing to love.
I would read more books in this series, as I think the universe being created would lend itself very well to multiple books. I just don't think that this was the strongest start.
If you're looking for a Terry Pratchett fix and you're already familiar with the Discworld books, I'd highly recommend "Nation." It's not part of the Discworld universe, and honestly, I am beginning to suspect that it is the best book he will ever write. It is really spectacular.