As yet, I've never truly gotten into Baxter's work - but after this particular collaboration, I'm very tempted to. A read with an oddly utopian bent, The Long Earth definitely won't be for everyone - but it was for me. It takes as its basis that staple of SF, alternate universes. The twist? Those of The Long Earth are empty of humanity, and correspondingly, its history (no alternate history here... mostly). Though a few of its relatives remain...
The Long Earth's history diverges from ours fully on Step Day, when a public blueprint for a 'stepper', a device allowing travel between these parallel universes, is released, and Earth responds... interestingly. New frontiers open up - bands populating the remote worlds with human settlements. Some Earth countries empty entirely. Some religions seek their respective paradises out in the Long Earth. And the Black Corporation and its partner, Lobsang (a Tibetan AI), decide to venture far into the Long Earth with the assistance of a 'natural stepper', Joshua, who does not require a device to step. This is the major plotline, but there's a loose focus here: there are a number of viewpoints, from a policewoman tasked with dealing with the threat of parallel worlds, to a secretary who simply disappears into the Long Earth, many of which are one-time-only.
It's more utopian than you'd expect. Humanity, away from the pressures of Earth, seems to treat each other - and its relatives - well: and honestly, after the dystopian trend of recent days, is kind of relaxing. The journey of Lobsang and Joshua is just that: a journey, not a war, more discovery than adventure. That's not to say it's tedious. Parallel universes containing every Earth that could be? Far from it. And it's frequently broken up with other viewpoints. But The Long Earth is not a fast paced novel. It's fresh, interesting, and a read for when you have a spare afternoon: not five minutes of excitement, which can be equally entertaining.
What of the characters? Well, suffice to say there seems more of Baxter than Pratchett about them - if you're looking for the wry, comic dialogue of Discworld, you'll be disappointed (there's no Vetinari here). But Lobsang and Joshua, and someone who I really won't spoil, play off each other well. Joshua is an interesting character. Born in another world, he's drawn to silence, and has... unusual instincts and desires in exploring the Long Earth - and interacts wonderfully with the more-than-human Lobsang, also with concerns for more than profit, but with an entirely different viewpoint. And thankfully, the cameos are a varied lot: telling a bit more of Earth's story, post Step Day, but this method of storytelling relies on that very variety to keep it interesting. And it succeeds.
There is a drive though. A threat, a mystery (or dozen), and the actions of those stuck on Earth combine to ensure that - however utopian - this novel is certainly not without compulsion. It is, however, without (much) resolution, and left me eagerly anticipating its sequel, so those who want at least some resolution might want to wait for that particular followup! But that aside, The Long Earth is a quirky book I have no hesitation in recommending - as long as you're prepared for more journey than action, and less cynicism than SF's used to. I enjoyed both, but they're not for everyone, and the cameo viewpoint style is - again - polarising.