Two or more Types of Ambiguity

I've had Eliot Perlman's Seven Types of Ambiguity out of the library for 4 1/2 weeks now and I'm only on page 47. It's a 623 page book so I'm going to have to get going if I'm going to finish it by the due date (June 24). It's unlikely. So, will it be just another book that I haven't finished reading because it has to go back to the library? And what's the significance of that? Does not finishing = not liking or valuing or enjoying? Probably not, in my case just because it takes me so long to read or maybe because I get distracted and read other stuff in the middle of the reading of the 623 page novel or maybe it's just too big and I can't carry it around with me so it ends up sitting in my office for a week just because I can't fit it in my bag to take home with me and read 'at my leisure'. I like the Perlman book. It's interesting and a bit of a page turner at the part that I'm at right now with a climactic kidnapping etc. yet I don't feel desparate to move ahead. I know what's happening in the book right now so I can just leave it and then say...ok, what's next. I really like the second person narration in Part 1 which is the only part I've read (I'm about 2 pages away from Part 2). It's second person so it's really bizarre and circular in a weird way. You can also get confused and think that the narrator (a shrink) is talking to you (the reader) so that's compelling and interesting. I don't mind percolating this book. I feel absolutely no sense of identification with the characters, I don't think. I'm not with them so maybe that's why I can't move forward very committedly. I don't think it matters. I'm just worried that I may only get to page 63 or 72 or optimistically, 88 by June 24 and not really have read the book. How much of a novel do you have to read to have read it? I dread buying the book mostly because I have so many books already that just sit there, mostly finished but unreread. I'm not much of a collector of books (except I like photo books).