If you took Cisco written exams before, prepare to see something unusual. First of all, don't look down at the “written” test just because it's a "written" test. Consider the following reasons to advocate CCDE:
1) They are going to run the CCDE test just four times a year.
2) Cisco is going to utilize just a few (2-4) selected VUE centers worldwide.
3) It's really hard to braindump *that* much of material, even if someone tries :).
Combined together with new tightened VUE security measures this should provide enough program integrity and thwart brain-dumpers (if they only could be defeated ;). Besides, there are no obvious solutions to each section - and I think that many alternatives are viable.
The exam itself it broken down in a few large "modules" or sections. Each section focuses on a certain network topology. They provide you with a *lot* of background information on each task: functional specification, SLA documents, business goals, justifications and constrains, engineering team emails, etc. You would probably spend a lot of time reading through the documents before actually going into each section. This is kind of unusual for folks that got used to the CCIE exam :)
During the test you answer well-known multiple-choice questions, justifying your design etc. Most notably, you can draw network diagrams using the Adobe flash engine that allows creating different topologies based on task functional specifications. To me, it was one of the hardest parts – coming with an unique topology, matching the business goals and restrictions. I doubt anyone (besides maybe Russ White) could end up with the same topology that the exam designers had on mind :)
The biggest problem of the test: after about 4-5 hours, it’s really hard to comprehend what’s your next scenario or task is about. Unlike the CCIE lab, where you know what you are actually doing, with the CCDE you may easily get lost in the labyrinths of your imagination. You start losing your concentration after reading so many documents and thinking of different designs. Releasing the exam in 8-hours format may be too much stress for most "normal" people. Hope they would make some adjustment for the production release.
From technical standpoint, the exam is mostly about generic Layer 3/Layer 2 networking technologies. It covers a lot of topics from IGP (ISIS, OSPF, EIGRP), BGP, MPLS, QoS and Security areas. It perfectly correlates with the written CCDE test, but this time you have to put all the things working together. The level of the understanding required to answer each question may vary from moderate to pretty deep (sometimes).
The last thing to mention, is that you can get a decent feeling of the real test by running the demo exam at : CCDE Flash-Based Demo.
After all, even though I’m not sure I’m going to pass, it feels like the exam was fun enough to justify a long trip :) Compared to CCDP, it's more about generic routing network design than Cisco "approved" template solutions.
Cisco is definitely on the right track, doing a great job by increasing their exam integrity. It could be doubted, whether CCDE actually tests design skills, but it sure is a great test on Layer 3 technologies implementation :)