Hey piedthepiper,
I haven't taken the Design Workshop for the 5.x series, however I did take it back in the 4.1 series and it was a great experience. The networking of the people, working through the design problems they give you, it was all great. However it gives you really good grounds on design choices, best practices, etc, it however is not the be all, end all to study for your DCD attempt. There is much more to prep for prior to attempting your DCD. I have heard many people take this course thinking it will line them up for a successful attempt at the DCD and if it doesn't they are upset. I think if you haven't had a great deal of design work in the past it is a great course to take as a starting point. Or if you have done design in the past but haven't done it in a while its a great refresher. However I would also suggest looking at some other study materials.
1.) The DCD Blue print, it is very LONG and has a tremendous amount of information in it, some of the "study" materials linked in it are not so great but none the less it will give you an idea of what can be asked on the exam.
2.) The community forums are another great place to look for study guides and other blogs where people have blogged about their experiences / study materials
3.) There is an extreamly great Study Group on google+ called VCAP-DCD Study Group with a lot of people who are also currently attempting the DCD or have taken it recently.
4.) Lastly I have created a DCD Simulator at www.virtualtiers.net which will give you an idea of what the exam is like. Also at the end of the simulator I have created a study guide with the materials you should know prior to attempting the DCD. The Study Guide I created is mostly the Blueprint with all the fluff stripped out of it. Not all sections in the table of contents have been finished yet but there is a few that dive into each topic area very well. The study pack is still a work in progress.
I hope this has helped, if you have any questions please let me know.
