If you are looking for a gentle overview of the ASP.NET MVC Framework, this is a solid book. If you are looking for a "Pro" book, there are better books available.
Over a third of the book is the Nerddinner walkthrough which is an excellent introduction to the ASP.NET MVC Framework. There are plenty of pictures so you don't lose your way, and the step-by-step instructions really help the beginning ASP.NET MVC Developer better understand the code, how it works, and why it was coded as such. Nerddinner will always be that beginner example we talk about and I love having it in book form.
The rest of the book starts to systematically look at the various pieces of ASP.NET MVC - Routes, Controllers, Views, and Filters. You basically get a very nice overview of each with a deeper-dive now and then. As a beginner book, I think the deeper dives are nicely placed and fine for someone who wants to use the MVC Framework out-of-the-box. However, for those who want to become an expert, extend the framework, or create an opinionated MVC Framework, you will be disappointed that the book does not go deep enough.
There are some smaller chapters on AJAX, security, unit testing, Webforms vs. MVC, and using Webforms with MVC. Again, good beginner material that gets your feet wet for more advanced and challenging books. The chapters entitled, Webforms vs. MVC and Webforms with MVC, feel like Microsoft product positioning, but they are still useful in understanding their thoughts ( whether you agree or disagree ).
Lastly the book has some quotes and personal thoughts by various ASP.NET MVC team members sprinkled throughout. I personally love those little gems as it gives you insight here and there into the development process and the decisions that had to be made. Reminds me of the book, Framework Design Guidelines. It humanizes the book, making it fun.
In conclusion, I think Professional ASP.NET MVC 1.0 is a solid beginner book. I think it would have been better named "Beginning ASP.NET MVC 1.0," but I have been using the ASP.NET MVC Framework for a long time, too.