The Long Earth promises much but sadly doesn't deliver, and is ultimately an average and unsatisfying read.

The central premise is certainly clever and intriguing; the basic idea and starting point in the novel being that there are a huge number of parallel Earths linked in a chain, easily accessible by making steps in two "directions" either east or west. All the other Earths appear devoid of human life, with subtle differences that increase the further you travel, and there is no way of taking iron (and so most technology) across into a parallel world. The book deals with mankind's response to this sudden availability of infinite space and resources but with limitations to development, and the subsequent exploration of this new reality.

Unfortunately the story and uneven writing do not live up to this interesting premise. The book is a collaboration between two well know authors; Terry Pratchett and Stephen Baxter, but rather than collaborating to produce a symphony they have produced a disappointing cacophony.

I'm a huge fan of Terry Pratchett but for me, sadly, he is the novel's weakest link - in particular his humour (usually one of his great strengths). What starts as a serious and promising Sci-Fi story by creating an interesting world that begins to draw you in, is quickly destroyed by sudden and abrupt sojourns into bizarrely out of place humour and totally unbelievable or unnecessary characters. For example: a computer that was a Tibetan monk in a past life, a religious community based around the idea that the universe is a big joke, an android cat and so on. All totally unnecessary, feeling like they would be right at home in a Douglas Adams novel but here are out of place and jarring, and manage to instantly destroy any illusion that this world could be a "reality". It may have been successful if the whole book held this humorous narrative, but the constant and obvious switching between serious sci-fi sections and silly sections does not work at all.

Despite this, the book did manage to hold my interest, and some of the ideas the two authors want to explore are served reasonably well by the central plot and story, although the contrivance is obvious and the plot is not particularly exciting. And even this falls apart in the final chapters with an ending that feels very rushed, and with one of the most important and seminal events of the book dealt with in one paragraph.

There are hints within the story that the authors have further interesting ideas and directions to take the books in the sequels. But I must admit, although the book held my interest enough to reach the end, it is not a journey I intend to continue.