It was co-written by Stephen Baxter, and if you're familiar with either his or Pratchett's writing then sometimes it's a bit too obvious who wrote which parts,

It was co-written by Stephen Baxter, and if you're familiar with either his or Pratchett's writing then sometimes it's a bit too obvious who wrote which parts, which for me at least led to a certain amount of immersion breaking dissonance. Additionally I would say that the series goes steadily downhill after the first book, but is still pretty good overall.