Checked exceptions are controversial mostly because a lot of the core APIs use them in places where it's pointless to check, like IOException.

Using them correctly can be great tho.

Mostly I think they are a mistake, like in ordinary application code instead of catching close to the throw you want to do a lot of

  try {
     ...
  } finally() {
     ...
  }

Occasionally though I have built something really sensitive, like an authentication filter for a web site which has at least 5 ways to log in and in that I have a hierarchy of exceptions and use checked exceptions heavily to document all the ways things can go wrong and felt like "the type system really has my back here" but that is like 5% of the Java I write.

Scala's ZIO also demonstrates that they're a great idea and can be perfectly ergonomic, but you need type inference, which Java devs were resistant to for a long time (maybe still are? I remember lots of "how will I ever know what `val a = new Animal()` is???"). If you infer the exception type, they're basically invisible except for when you forget to have some place in your program to handle them, which is exactly what you want.