at 60+ pages it's something that will take me a bit of time to go through. But on a first glance it looks good, i.e. similar quality to their blog. The ebook takes you through the whole process of thinking about your product, what it needs to do and what you should think about so that it will actually do it.

I'm sure a few people might complain about the fact that you have to invite 2 other people to get the book. But I'm also sure that people here are smart enough to get around that if they really want the book.