They say that writing a book is a hard way to make an easy living. This is especially true for technical books, which tend to have a short shelf life.
For me, the process was made easier by having three great seasoned authors to work with. We updated all the existing chapters of this 4th edition to cover ASP.NET MVC 4, and we've added three new chapters covering Membership & Security, Web API, and the building of the NuGet Gallery site using MVC. I like to think of this book as my Microsoft swan song. :)