Personally, I would leave reading the book. Although I'm not sure it would matter as long as you knew it was not a literal adaption.
But it's enough to say that the primary character's backstory and arc in the film is completely different with a totally different ending to the book.
So there's no real comparison to make.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist