Excellent
Great resource. I tend to be overly aggressive, and read this to help me tone it down and just be assertive instead. I'd assume it would work equally as well for a passive or passive-agressive person looking to become more assertive as well. Contains lots of information on related behaviors, even gives some tips on controlling your breathing to calm you down in stressful situations that can lead to less than ideal responses on your behalf. Some chapters were irrelevant to my needs so I just skipped through them, but I'm sure they'd be useful to some.

The Assertiveness Workbook
This is an excellent book and very realistic and practical for use with day-to-day interactions with others.

BUY IT NOW!
If you're reading this review, you probably suspect that you have a problem with assertiveness, so take the first step towards improving your life by purchasing this book. If you have a problem saying no to unreasonable requests, if your legitimate and reasonable requests for what you need are repeatedly denied, ignored, or trivialized, if you feel surrounded by manipulative, controlling people, if you have been in a long-term verbally abusive relationship, if you are easily intimidated by aggressive people, or even if you're just mildly curious, this book will be invaluable to you. It's not just a quick read, though. It has thought-provoking exercises to help you determine why you have difficulty asserting yourself as well as practice exercises to prepare you to be assertive when the need arises. Even if you don't think you need improvement, this book is a great resource on communication.

Clearly to the point
Excellent resource for how to deal with PA's and others-the book's no nonsense approach (yes, it's hard to change and yes your significants others will resist you), exercises, and examples give you inspiration without alot of nonsense and over the top 'you can do it' every paragraph.
Accessible and easily readable, this practical guide will help you get what you need or establish your personal boundaries without all the new age style rhetoric.

Excellent!
This book is by far the most helpful book I've ever read. It is very informative, but in plain words that almost anyone can understand. The exercises it suggests really do help. I'm only half-way through it, but I've already made significant changes in my behavior. It really helped me understand the different communication styles and how to tweak my style to make me more satisfied with my communication with others. It's so simple to do! I've always been lazy about change or given up too early, but this truly couldn't be any easier.