It's been a while since I used self-signed certificates, but experience used to be just about right. You hit the page and browsers throw a big fat warning. You add an exception, basically acknowledging that this is a certificate you trust (exception is for the cert, not any cert on this domain ever), and as long as the certificate doesn't change, your trust is at the same level it was on the initial load of the page.

The UX problem with self-signed certs is that you start expecting to accept them, so when that site asks you again to accept it while you are browsing in a cafe on a public WiFi, your browser would need to know that now you are on untrusted network and that you should better watch out.

Which is why LetsEncrypt came to be: it provides at least some chain of trust without any extended validation, which is a bit extra on top of self-signed certs.