Not OP, but here are some things I've personally experienced:
1. Supposedly more secure challenge types such as TLS-ALPN-01 are far from stable, as the current incident shows. Your cert can be revoked at any time through no fault of your own. After being burned by TLS-SNI-01 the last time, now I refuse to use anything other than plain old HTTP-01 and DNS-01.
2. As soon as the version of the Linux distro I was using (not in my power to change!) reached EOL, certbot suddenly refused to renew, despite the fact that I'd been using more or less the same version of Python and certbot for a number of years and the HTTP-01 challenge requires nothing fancy at all. Why does everyone these days insist on making ops decisions for other people?
3. On a server with existing nginx virtual hosts, certbot injects configuration directives including stuff the nginx team officially recommends against, such as `if` statements. It frequently breaks existing configuration such as rewrites and redirects. After seeing this a number of times, the only conclusion I can make is that certbot has no idea how to manipulate nginx config files.
4. If I have multiple domains pointing at the same application, and remove one of them at a later time, certbot is oblivious and repeatedly fails trying to renew the certificate that now contains an invalid domain. Again, certbot doesn't know how to work with nginx.
Maybe 3 and 4 can be improved if ACME was integrated as a proper nginx module instead of certbot trying to change things from the outside. My experience as a whole, however, makes me feel that the LE/certbot teams are rather cavalier about the commitment to stability they need to make if they really want to become an essential part of the world's internet infrastructure. If you want to be paternalistic about managing TLS for people who don't know how to do it, at least try to do it properly!