I passed my 70-516 exam yesterday with a score of 860. Not as great as I would have liked but not nearly as bad as I had feared. Overall I'm pleased. For what it's worth, I followed the same route many others have followed in preparing for the exam. I started with the MCTS Self-Paced Training Kit (Exam 70-516): Accessing Data with Microsoft .NET Framework 4 which I obtained through the O'Reilly Safari Books Online. The nice thing is you also get access to the CD contents which includes a copy of the MeasureUp testing software so you can take practice exams. I imagine it isn't as up to date as what you would get if you went straight to MeasureUp or if perhaps the included copy of the software has a smaller question pool, but it was still helpful.
In any event, once I had finished going through the book and making sure to actually run through the examples and make an effort to answer the questions at the end of each chapter without looking back, I started going through the links from this blog post by ondrejsv. For each link, I would read through the linked article and then either follow relevant links in a new tab or open a new tab and search for a topic that seemed to be potentially of interest. Think of it as doing a depth-first-traversal of the MSDN articles. What I found was that there were interesting bits of information that were uncovered in the MSDN articles, especially in those containing sample code, which dealt with some topics in greater detail than the material covered in the book. In that way, the book was a good baseline for preparation but the MSDN links fleshed things out a bit more.
In conjunction with this, I continued to go through the sample tests. I kept a text file open and jotted down items that I was having difficulty with and would then spend time doing searches online for additional material covering that topic, both within and outside of MSDN. Additionally, I started creating mini-projects. Initially the projects would be very straightforward, switching back and forth between thick clients and web clients. Then I expanded to web services with various clients, splitting the EF entities into their own assembly, and so on.
I'm now considering which I should pursue next, 70-513 (covering WCF), 70-515 (Web apps) or 70-511 (Windows apps). If I'm going to shoot for MCPD, I will definitely need 513, but would need to choose which I would specialize in, Web apps or Windows apps. Still, not every project will involve WCF so perhaps for the short term I would be better off picking 515 or 511.
In any event, I've been told that 516 is considered to be more difficult than the other exams. Not having taken the others nor even studied them, I can't say. For those who have, I'm curious what your opinion is.