Loved this book too. It has a really helpful survey at the start that helps you to see whether you are 'highly sensitive' or not.
I must admit that when I read it, suddenly a lot of what i thought were random challenges in my life actually made sense. I felt as though it was written just for me. One big thing, I remember, was working out why I felt exhausted by the company of lots of other people, rather than on a high, like everyone else seemed. I love meeting new people, and spending time socialising, so this has always foxed me. It was good to realise that I just need smaller groups and smaller doses to really enjoy myself.
Blathering on now. Anyway, I will be re-reading it soon. Good luck with it.