Awhile back I wrote a blog article about “Everything you wanted to know about NTP” on the MTIn blog.
Cloudflare has announced its NTS service, which is open to everyone. If you have an NTS client, point it at time.cloudflare.com:1234. Otherwise, point your NTP client at time.cloudflare.com. More details on configuration are available in the developer docs.
So what are the drawbacks? Right now there are very few NTS clients. Secondly, you don’t want to put all your eggs in one basket. If your networks rely on NTP, which most modern networks *SHOULD* be, then you are trusting someone else for a critical piece of your infrastructure.