It depends on the variety. All the supermarket bananas I've tried in the US and Australia are way too cloying and lose what little complexity of flavor they had once they get that ripe.

However, when I did study abroad in Costa Rica, I ate a lot of different kinds of fruit out of people's backyard fruit trees. All the best bananas I tried there had entirely black peels (no yellow at all), yet the fruit was firm and not overripe, and they were so indescribably good that they completely ruined supermarket bananas for me. I no longer eat bananas.