Before I go to Sleep

SJ Watson's thriller relies on a very clever premise - if you suffer from amnesia and your memory starts afresh every day, how do you know what is the truth and that people are who they say they are.
Christine wakes up and has to piece her life together through photographs and written reminders on a Groundhog type daily basis. This could get repetitive and dull, but the excitement is that every time she uncovers a little bit of new evidence or hint of a lie, will she be able to note it down in time and then re-discover it before she goes to sleep.
Written in the first person, you are put into Christine's blank mind, but, frustratingly, you know what has gone before. Gradually you build up a picture of mistrust with her husband, Ben, as she discovers things that have been kept from her and with Dr Nash, a neural psychologist, but is it just Christine's natural paranoia following her accident? Her journal is a means for her to record her suspicions and remind herself of things that have recently come to light.

Now I have a confession to make about my blog.
Often I have read the book ages ago and when it's announced that it will be made into a film, I debate over whether I want to re-read something I have already read. Time's too short and there are too many books out there.. With Before I Go to Sleep, once you know the big twist, its not a book that begs for revisiting to be honest, so I cannot say for certain what differences there were between the novel and the adaptation. Knowing the twist didn't necessarily spoil the film - having foreknowledge made Colin Firth's character more intriguing and I enjoyed watching his performance.
Two things I will note, however.
One is the obvious change from a written diary to a video diary. Does anyone keep a video diary except for people in films? Of course this makes better viewing, but thinking about it it also makes a better and easier record for Christine. Writing and reviewing a diary every day is taking precious time away from someone who only has 18 hours available to them.
Skipping through a video diary is not only is quicker, but is instantly reassuring as an amnesiac - you can see its you speaking and (clever in the film) you can notice any changes to the surroundings.
The second note is really the ending, which is all far too convenient - further head injuries reawaken her memory and she is able to recognise and remember her son at her bedside. I wish I could forget the last 10 minutes of the film, as it spoils a neatly plotted and presented thriller.