Honestly, one of the few nice things I can say about the Axon's design is that the phone feels sturdier when it's fully open than I had expected; the two screens sit flush with each other, and the hinge feels strong. To actually make use of both screens, you'll have to tap the "M" (you know, for "multitasking") key next to the standard navigation keys. This is where things start to get wild.
In addition to using the Axon M as you would a normal phone, there are three ways to make use of that extra screen. You can mirror the contents of one screen onto the other, so you can, say, watch a YouTube video with someone sitting across from you. There are some theoretical business use cases too, such as propping the phone up like a tent and walking someone through a PowerPoint presentation, but this is easily the most forgettable of the Axon's multiscreen modes. Dual mode, which gives you the power to run two distinct apps on their own screen, is more obviously useful. It's a year old at this point, but Qualcomm's Snapdragon 820 chip plus 4GB of onboard RAM keep pairs of apps moving with respectable fluidity. Occasional instances of lag are to be expected, but giving two apps screens of their own generally works well.
You definitely shouldn't run two games side by side, but everything else is fair game. I've taken to leaving YouTube running on one screen while I dash off emails in another. And trying to get through The New York Times Saturday crossword puzzle isn't so difficult when I have Google search results for tricky clues beneath it. For all the quirks and strange design choices, multitasking on the Axon M can be useful. Here's the rub, though: The primary way people multitask on their smartphones is by jumping in and out of different app windows, and despite everything, we've gotten good at it. As a result, I quickly ran out of reasons to run different apps on these screens. After a while, I was doing it just to do it, not because using both screens made me any more efficient.