What do you think about union types and intersection types?

http://ceylon-lang.org/documentation/1.0/tour/types/

What do you think about str interpolation?

Void hello() {
  // looks more simple
  echo("Hello, you ran me at "
         process.milliseconds
        " ms, with "
         process.arguments.size
        " command line arguments.");
}

http://ceylon-lang.org/documentation/1.0/tour/basics/#string_interpolation_and_concatenation

What do you think about union types and intersection types?

Cool, but I can't recall where I actually ever wanted something like that.

What do you think about str interpolation?

I don't find it is as clean and readable as the $foo syntax. Their reasoning is that it is more difficult to tokenize, and that is very true. But don't think I could live without proper string interpolation.