I'm about 200 pages in now and really enjoying it. Don't want to say much in case no one's started it yet but the first few chapters are very very different to his previous work, stylistically. Definitely wasn't expecting chapter 9, haha. It's hard to tell how unfinished it is really - so many of the chapters so far are like short little vignettes, a page long or so, which introduce characters etc, but it's impossible to say whether they're deliberately short for that reason or if he was intending to develop them further...
There's hardly any footnotes either, which is a bit disappointing, as i love those in all his other stuff. I guess he might've added these later or something.
PS the UK cover is SO much better than the US one.