This book has so many potentially life changing tools in it, but you really do need to be flexible in how you use it. It is not a self-help book just to be read, you really do need to read each of the exercises and put them into practise and then find the ones that you can relate to and then make them part of your daily or weekly routine.
I would say, stick with it and it will transform your life on some level. To say it is a mish mash of existing tools is unfair as the author has gone to great lengths to research current thinking and find methods that when linked together can bring peace and contentment and initiate a change in thinking and behaviour that can have long lasting effect on inner contentment.
I have only been using the methods for a few weeks and can already see a change in my thinking and in my relationships. Just reading all the inspiring quotes alone can inspire you.
So my summary would be - this is a great book, but you have to apply the exercises, find the ones that work for you and stick with it. I would be very surprised to find anyone that had actually done this, that could then say that nothing in the book helped them find peace and contentment.
There is something in there that will resonate with everyone - you just have to dig a bit deeper to find it.
I highly recommend this book if you really want to find peace and contentment without making major life or personality changes.
The focus of this book is how to love yourself just the way you are, stop beating yourself up and learn how to love your inner pessimist.