If you are working on ASP.NET now and want to get to speed quickly to ASP.NET 2.0, then this may be a good book to try. This book from O'Reilly is not aimed at new ASP.NET developers, but rather people who just want to learn the new ASP.NET 2.0 features.
The book is an very easy read and cleanly written, covering most of the new ASP.NET 2.0 features like Master Pages, Themes, Web Parts etc. It contains a lot of pictures and screenshots and is written in a single step at a time format. This means you can actually code as you read the book and learn the new features. Another advantage is this style is that if you are just interested in a particular feature, you can just skip to that chapter and read through without any difficulty.
But this approach also has its disadvantages. It can sometimes seem too long and it takes quite a few steps to actually get to the meat of the stuff. So if you are the impatient kind, you may find this book a bit too slow. And I personally do not find the margin notes very useful, but I suppose preferences vary.