I really enjoyed it as an audiobook (im 27 so perhaps not the intended audience). It really covered some quite deep topics, and I wonder if it was ideas Pratchett was struggling with too - or perhaps I'm reading too much into it. Either way he built a wonderful world; very different from his discworld books which I never got in to. I would say that I felt the ending was a bit rushed, mildly unsatisfying, but perhaps inevitable. There are very few times I have genuinely enjoyed an ending.