In my tests so far it has worked as promised. It can distinguish and produce different accents and tones of voice. I am able to speak with it in both Japanese and English, going back and forth between the languages, without any problem. When I interrupt it, it stops talking and correctly hears what I said. I played it a recording of a one-minute news report in Japanese and asked it to summarize it in English, and it did so perfectly. When I asked it to summarize a continuous live audio stream, though, it refused.
I played the role of a learner of either English or Japanese and asked it for conversation practice, to explain the meanings of words and sentences, etc. It seemed to work quite well for that, too, though the results might be different for genuine language learners. (I am already fluent in both languages.) Because of tokenization issues, it might have difficulty explaining granular details of language—spellings, conjugations, written characters, etc.—and confuse learners as a result.
Among the many other things I want to know is how well it can be used for interpreting conversations between people who don’t share a common language. Previous interpreting apps I tested failed pretty quickly in real-life situations. This seems to have the potential, at least, to be much more useful.
Decades ago Douglas Adams already knew inserting gratuitous "Genuine People Personalities" in devices would be so annoying it would be comical (http://www.technovelgy.com/ct/content.asp?Bnum=1811). I don't get why OpenAI keeps releasing demos that make their product look comically dystopian.
Imagine going to a restaurant and not getting a menu, instead having the waiter stand there and tell you every menu item.