I wish I'd had a copy of this book when I was suicidal. It's full of simple, practical ideas for keeping yourself safe and beginning to feel better. The crisis plan is especially good, and easy to follow even when you find it hard to think straight. The only reason I gave this book four stars rather than five is that I came across it after I'd recovered, and haven't tried out all of its techniques myself - but from my experience of what did help me, they're all excellent.
"How I Stayed Alive..." would also be a useful self-help book for people who self-injure, even if they don't feel suicidal. Most of the suggestions work just as well for getting through the urge to self-harm.
I've heard two main criticisms of this book. The first is that the author wasn't "really" suicidal, but just attention-seeking. I disagree. All suicide attempts should be taken seriously, even if the person's done it many times before, or chooses to get help afterwards. In fact, the more unsuccessful suicide attempts a person has made, the more likely they are statistically to die by their own hand. And seeking medical help after one has taken an overdose can, tragically, be too late. That's why books such as this one are so important, because they help prevent the suicide attempts in the first place. Admittedly, this book is aimed mainly at people whose suicidal thoughts and feelings come and go, and who need help in getting through those difficult times without harming themselves. Someone who is unrelentingly suicidal and not interested in alternative courses of action probably needs to be in hospital, not reading a self-help book.
The other criticism I've heard is that not all the book's suggestions can be used by everyone. That's true. A lot of the suggestions regarding emergency mental health treatment and helplines just don't apply to the UK. But "How I Stayed Alive..." also contains many techniques that require nothing more than a copy of the book. I'd encourage anyone who uses this book to adapt the crisis plan to their own particular situation, removing any steps that aren't appropriate and adding in anything extra they can think of - but it really is an excellent starting point.