A lot of people mentioned this book felt like a travelogue with a sci-fi twist. I didn't really understand that until I read it.
The pace is slow, almost relaxing. Conflict arises, but it's dealt with quickly and things continue. The premise and first few chapters hint at action and drama and excitement, but the book never really delivers it. I can't say that's my main problem; my main problem with this story is that I just didn't care much about the characters or anything that happened to them. I didn't care about the Long Earth, or the troll migration, or Happy Landings.
The worst thing I can say about this book is that it's underwhelming, and I imagine I'll soon forget it. It's not a bad story, and I was entertained. The entire book just feels like a prologue to the real story.