As of January 22, 2020, the DP 100 exam has been updated. See DP 100 Updated post.
I took and passed DP-100 during the beta period. I recorded a live video talking about my experience. Below is that section of the live video. Also, here are the main topics:
- Azure ML Studio
- Machine Learning
- High-level knowledge of Azure Products
Also, if you want a checklist to prepare for the exam, I have created one, it is free.