For me, I'm reading more books because my e-reader is with me everywhere I go. The unfolded mode is fantastic for reading. It's obviously great for video too, a nearly 8 inch screen in your pocket is a big upgrade. Honestly it's big enough to comfortably use a terminal app like Termux as well. It's excellent for any note taking app you use. I use Obsidian, having more real estate is really important for long, detailed notes, plus tabs are easier to navigate there and in the browser, which of course also benefits from the bigger screen (most websites look better on bigger screens).

> That’s not a killer use case, that’s just running two apps next to each other. There are tons of phones and tablets that can do that.

But they aren't iPhones.

Running two apps next to each other isn't practical on a normal sized phone. That's why the Duo folds out into a larger screen.