For a while I wasn't sure if this was a flaw or a unique way of structuring a story.
After I read Murakami, though, I realised that what Neil Gailman was trying to do was not to structure in the manner of a genre novel, but instead as a literary novel - where the protagonist is not necessarily important as anything but a way for the reader to experience the environment of the story. Ultimately, the protagonist serves as an observer to the story, rather than an active driver of it.
The reason I was so confused is because I hadn't read any literary fiction for a long time, and certainly not while learning about the tools of the genre writer, not least when it came to structuring. Having read a couple of literary works since, I feel I've a better idea of what Gaiman was trying to achieve.
IMO it still makes for a less fulfilling novel having an underdeveloped protagonist - but Gaiman's worlds are always very richly populated, so it's a case of give and take in different areas.
Just thought I'd mention that.