This is not your typical Terry Pratchett novel. 
 It shouldn't need to be stated in a novel that was co-written with another author, but I have heard a lot of people express mild disappointment after reading The Long Earth because it's not as funny as a usual Pratchett novel, or it's too science fictiony. 
 The Long Earth was co-written with Stephen Baxter, and it would be wise to go in without any expectations. 
 The story starts off a little disjointed, telling a number of different tales of "stepping" - the ability to move into seemingly endless alternate versions of Earth - revolving around an event called "Step Day", where the knowledge of how to step is suddenly spread to the whole of humanity. 
 After the initial few chapters, the story begins to settle into the main tale of one "natural" stepper, called Joshua Valiente, and his travels deep into the Long Earth with Lobsang, a Tibetan motorcycle repair man who was reincarnated as a powerful artificially intelligent computer, with only the occasional branching into other stories. 
 Of all the stories initially presented, the tale of Joshua and Lobsang was, to me, the most interesting, so it was a welcome shift in the in the novel. As the pair explore the Long Earth, we are also treated to a sub plot of how the advent of stepping is affecting the Datum - the original Earth. 
 While there are few parts of the writing that seem to be very clearly Pratchett's doing, the story does have it's fair share of comedy, for such a serious story. I had not, until now, read anything by Stephen Baxter (though that will change after reading The Long Earth), but I found the parts that seemed most un-Pratchett-like to be just as enjoyable as the rest. 
 The pace is quite slow, but that suits the story well as the details of stepping and the Long Earth are fed to the reader at a consistent pace, while sprinkling in enough mystery to keep the reader wanting those details when they come. 
 Technically speaking, the story is as tight and well-written as you would expect from two successful and respected authors, and all of the characters have depth and believable dialogue. 
 The story ends wide open to a second novel, and I for one will be purchasing it if such a novel is written.