Thanks for posting - this looks like a nice introduction for beginners, I agree building a real app is the best way to teach building web applications. It's probably really difficult to pitch this right and include enough detail for beginners without making it cluttered for those who are more familiar with programming or the Go language. Perhaps there's some way to hide some of the content and only expand explanations if the reader wants to (since it is html)? At the moment if you're familiar with some of the concepts there is a lot to wade through (e.g. box Box 2.5). I think perhaps the point 1.2 should make is that if you're familiar with all of Go/HTML the book isn't for you, but if you know HTML but not Go for example it would be a useful introduction?

Do you have a proposed table of contents somewhere?