Just passed all four SharePoint 2010 exams in the last two weeks. In my opinion, if you have more than two years experience on MOSS 2007 (include WSS 3.0), and at least one month experience on the new features of SharePoint 2010, those exams are not hard.
So far there are not much study materials for these exams. I went through 80% of Professional SharePoint 2010 Development, and learned a lot from it. This book is perfect for senior SharePoint developers, but not sure whether it is suitable to new learners.
Just like other Microsoft exams, new features are always more important :-)