I *loved* this movie, and really should read the book. I remember hearing that the opening scene was supposed to be really confusing if you hadn't read the book, but honestly, I found that complaint confusing, because I had no trouble following things at all. The movie does demand a lot of attention, like you said, but I was so riveted that was no problem anyway.

Of course, one Amazon reviewer didn't realise it wasn't set in the present day, so.

That's ... unique.