On one hand, it looks pretty cool and convenient. On the other, using a DNS server requires a lot of trust.
Giving some unknown company the ability to trivially man-in-the-middle your connection or sell your browsing history is pretty scary. The fact that their code is open source helps a bit, but there's no way to tell whether the code running on their servers is the same as on github.
I'll stick with my pihole/hostsman [0]