I have taken the exam and cleared. This is for those looking to take the exam. I wanted to share my take on it so it helps out others looking to take it.
It is not difficult, though it does take a bit of effort to pass. Its not as hard as PMP but definitely not very easy as well. You need to have gone through the course material and take a few practice exams to be fairly sure of having a good chance of passing. I already have PSM I so had basic knowledge of Agile already, It helps to have it but is definitely not a prerequisite for DASSM.
I went through the WoW book at a high level and took a few mock test to help pass the test in first attempt. It needed about 2 weeks to go through and prepare. My exam was reimbursable by my organization only if I passed. So it made sense to take a invest in a few mock tests to increase my chances of clearing in first attempt and not paying out of my pocket for any subsequent attempts (which are not reimbursable).