As a new product manager, I enjoyed gleaning insights from a variety of perspectives (the contributors include executives, consultants, authors/bloggers, and trainers as well as product managers). I appreciated reading what each contributor felt was important about product management, and why. It gave me a broad perspective on the subject of product management and I came away with plenty of notes that I'll use in my current role as a product manager.
A few pieces of advice to give you a feel for the advice that I found both useful and insightful:
Saying "no" because the customer isn't always right: There are times when saying "no" can be mutually beneficial. An example from the book talks about how saying "no" led to a call from the CEO expressing disappointment, yet once the customer got past their initial disappointment, they built the capability themselves. This is much better than leading a customer on, letting them think that a feature might make it in at some point in the future.
If you want to improve your product, talk to a competitor's customer. "...they'll tell you why they didn't buy your product, and what you would have to do to your product to make it worth purchasing." Conversely, customers of your own products typically point out things they don't like or would like to see added or fixed - for free.
A key test of your (as a product manager) being a CEO of your product: "When a question arises about product direction, all eyes turn to you. If that's not happening, ask yourself if you're being a true product leader."
If you're a product manager, this book is a must read!