Very watchable and compelling.
But.
The plot holes and general not feeling right got on my tits.
Apart from the blood group question (I started a non spoiler thread on Chat) - shock horror- husband doesn't know wife's blood type; there was her going to hospital covered in blood and then remaining covered in blood for hours or days afterwards. Being wheeled into a room full of maybe 12 FBI agents to talk them through her 'kidnapping, captivity and rape'- where she held court and dictated the show. (maybe hospital bed, shower after examination and treatment, maybe a one to one with a specialist rape councillor would be the reality?).
Then she makes it all the way home covered in blood too!
Also assuming in the book that 'Amazing Amy' plot line was supposed to explain her psychopathic tendencies - it fucked her up forever...?
Also I'm assuming that throwing away all the different pens from the car was because she'd used them to fake the diary?
The stalker guy - is he supposed to be this side of nice to make you realise he's not the crazy she made him out to be? I thought he was a bit on the fence and not a 'loser' enough to convince she would have dumped him - rich intelligent, accomplished, erm.. Attractive, has a beautiful house.
And the cat - is he just a casual observer 
Will read book but I think the film should 'stand' as is