The 70-515 Training Kit was based on the 70-562 manuscript, so you’ll recognize quite a bit of it. If you’ve already worked through the 70-562 TK, I’d tell you to skip 70-515 and spend a week working with jQuery, LINQ to Entities, Dynamic Data Projects, and every aspect of MVC.
If you haven’t yet read through 70-562, scrap it and use the 70-515 book instead. In addition to adding the topics I just mentioned, Mike and I added quite a bit of content to the previous topics and fixed lots of little nit-picky mistakes that always work themselves into a big complex book like this. Not that there were big problems with the 70-562 Training Kit; it got good reviews. We found minor errors like C# classes with the wrong capitalization, etc–stuff that managed to slip past our reviewers.
Let me know if you have any other questions.