Personally I believe it’s a must-read-me book for anyone who is interested in web design, disregarding the fact if they are beginniers or highly experienced geeks. Both can find answers to questions they could ask, compare described examples, see flaws and advantages of existing forms in well known services, and finally choose the solution that fit best the end users.
The book is relatively short but full of suggestions supported with a lot of examples (screen shots). It is dived into several chapters describing individual aspects of web forms, i.e. labels, inputs, actions, help texts, error and success messages.