The book is almost exclusively focussed on forms on public websites, such as eCommerce or social networking sites. As a result, the studies cited and undertaken by Wroblewski investigate how users interact with forms they are not accustomed to.
In other words, the goal of the book is to optimize forms for novices, not necessarily for proficient users. In itself, this goal is laudable, however, it ought to have been made explicit. As things stand, it is uncertain if all or which parts of the advice applies to forms whose users interact with them regularly and know them well.
By the standard of this book, complex forms are a mistake. And this may well be true for public facing sites. The situation is different for in-house applications that incidentally have a browser-based user interface. On these, unfortunately, the book remains silent.
I'd like to have seen a discussion of interactive controls beyond the native HTML text fields, drop downs, check and radio boxes. I'd like to have read how to make the best of fluid or elastic page layouts, as it is, all examples assume fixed-width layouts. A chapter on the construction of forms using semantic HTML and CSS wouldn't have been out of place either.
What's missing most of all is an extended case study that goes through all the stages of designing a realistically complex form.
After all this criticism, I'd like to point out that what is there in the book is very solid. As things stand, though, there remains much to be said.