I don't know what I expected when I started reading this book - but it seemed like an interesting topic and hey, we could all do with a little less stress, right? Carnegie takes a very clinical, ordered approach to worry. What are it's causes? How bad can it actually be? Ignore the negative and focus on the postive etc. As a 'life philosophy', I don't think it really works. With the title he implies that worrying and living are mutually exclusive, that is to say you must be doing one or the other - I believe that worrying is part of living.
However, it's important to keep things in perspective, so I'd recommend this book as a 'reference' copy - keep it in the bookshelf, and bring it out only when you need reminding that it could still get a whole lot worse.