The Admin exam
This is the part that requires a lot of practical experience... This was the first reason that I've tried this path… to prove myself my technical knowledge.
And I think that this is the right way to do a technical exam… You must demonstrate your technical capacity… not your memory capacity.
On the VCDX3 path this exam was (on October 2010 it was retired) composed by a part of close questions (very deep on some technical arguments) and a part that is a real environment with some tasks to complete.
The second part is very similar to some kind of Cisco exams, or some Novell Linux exams (like CLP) or what was (as I know is not more available) Microsoft practical exam on Active Directory (83-640).
The most interested aspect is that you have a full system (not a limited simulator) so you have all commands and also the help on it!
The advantage is that your have to wait some weeks to know the results… This part can be improved, because Novell CLP and Microsoft 83-640 exams were able (I do not know in which way) to give the results after the exam.
For the VCDX4, this exam is the VCAP-DCA exam and now (it is available from October 2010) is based only on practical tasks (so no more the close questions part)… so is a very technical exam!
Unfortunately I was not able (due to other commitments) to participate at the beta period… and now I want first to do the VCAP-DCD exam (and only I have some spare time or a closest center also the DCA).
Exam Center Locations - http://mylearn.vmware.com/mgrReg/plan.cfm?plan=18206&ui=www_cert
Other user's experience in Admin exam
Old Admin exam
New DCA exam