I just passed the VCAP6-DCV Design exam 3V0-622.
I hope the following information will be useful for others candidates.

Exam platform

Be familiar on how the exam looks like and how the scoring system works before attempting the exam.
VCAP Datacenter Design Simulation
(If the link is not working, in the exam description > “How to Prepare”>”Practice exam”)
Scoring for VCAP6 Design Exams
VCAP6 Design Tips, Tricks and New Features The “+” key is a timesaver.
Unofficial simulator

Study guide

I used the “VCAP6-DCV Design – Study Resources” from Andras Herceg.
It is a very good post and if you follow all links you will get a solid foundation for this exam.

Experience

PROS:
The interface was fast and without bugs for all tasks.
Enough time. I had 30 minutes left after reviewing the 18 questions…without including the 30 minutes extra for non-native speaker.
Relevant content.

CONS:
I think this feedback extracted from the “VCAP6-DCV Design google + group” summarises it perfectly:
This meant that there was a lot of guesswork about how to express the answer using the tool. I don’t mean guessing because you don’t understand the subject, or can’t provide a good answer, I mean guessing because you don’t know how the tool needs you to express the answer!
For some questions, even with the information on how to connect the elements, it was really difficult to understand what was expected in this context.

Following my previous experience with the VCAP5-DCA exam i have really studied a lot for this exam and it has paid off.
First, as a consultant, I have now a deeper understanding of many topics.
Second, regarding this exam I was really prepared.
For 16 questions I was confident with the topic.
For another one I had to bring back memories about a PDF I read a long time ago.
For the last one I made a mistake due to a lack of understanding of a third party technology.
(And it will be easy to avoid this mistake by checking the information in a real life scenario)

But despite this i just “barely” passed the exam.

Automatized scoring system. Good idea?

Design is really subjective, and in my opinion an “automatized scoring system” is not really suitable.
Example:
Component A should be connected to 3 components B and give you 7 points
(Simplified 1 per shape 1 per connection, 4 for the shape 3 for connections)
If instead you connect one component B to 3 components A, you made “one” mistake (mixing A and B).
However it will cost you all points.
3 (Shape A and Shape B there + connection)
-2(Missing 2 Shape B)
-2(Missing 2 connection)
-2(2 Shape A too many)
-2(2 connection too many)
=-5
If a human was reviewing and giving a score for this he could:
Give half of the points if the focus of the question was to show one shape connected to 3 others in the right location.
Give 0 if the goal was really to know the difference between A and B.

A “design exam” between the VCP and the VCDX is useful however maybe something can be done to make this exam more “fair”.

Could it be checked by a human?
Make all components available for each question…and let a human (or many) review all design.
Unfortunately it will probably never happen.

Can VMware provide mock exam?
I guess VMware will keep the exam as is.
But at least with mock exam, it will help candidate to “think” in the VMware way.

Summary

A good preparation is mandatory for this exam, even if you have already experience you must learn at least how works the scoring system for this exam.

However even a good preparation doesn’t ensure a pass, even for a skilled designer.
Due to the “automatized scoring system” you can only pass if you think in the way that the exam is expecting you to think.

Good luck for future candidate.