The first ~200 pages were great, terrifying, made me scared of the dark. ~200-350 were a great adventure, some fun plays with books as a medium. But after around 350 the book becomes almost a literary analysis of itself, a parody of itself revisiting the same ideas again and again, each time the punch weaker and weaker until 200 pages later it finally ends where it should have 200 pages ago.
It's a good book, any book that's over 600 pages that gets read in a week and half is a good book, but I can't in good conscience recommend it
If you do read it, get a physical copy, and get it in colour.