Sony announced their dual-screened S2 tablet today. It's not the only twin-screen tablet, but considering recent ill-conceived efforts from the likes of Acer, Toshiba and Kyocera, we're a little skeptical. With the S2, Sony's basically cut a 10-inch screen in half and stuck a hinge in between. How much of a benefit can two screens provide over one?
First and foremost, no operating system powering any of these dual-screened tablet devices was actually made to run on a dual-screened device in the first place. The Acer Iconia runs Windows 7 (which is barely functional on a touchscreen device, period). The Kyocera Echo and the S2 both run (or will run) versions of Android, which has been designed for single-screen devices. The recently shitcanned Kno did run custom software made for the device, but their entire OS was designed around using textbooks, which was super limited to start.
If we're talking about how dual screens can benefit apps, they can be designed to act the same regardless of the form factor anyway. The now-terminated Microsoft Courier showed some interesting ideas about how a dual-window approach could be effectively used from a content creation standpoint. But if anything, that's a design metaphor that would work just as well on a standard tablet. If you want a single-screened device to act like a dual-screened device, it's just a matter of programming (just look at the multi-paned design of most tablet email apps). I don't need a hinge in between two screens to sell me on the illusion of a notebook.
I'm sure some will argue that a dual-screen tablet is good as a keyboard or gamepad, but have you really used an on-screen keyboard or gamepad? They're totally functional, sure, but no amount of angling and configuring will make typing on a dual-screened tablet definitively better than on a slate, and it certainly won't offer anything comparable to an actual keyboard.
There are other hardware disadvantages. The gap between two screens is distracting. No matter how well you design an app or operating system to work around it, that gap will never disappear from your mind. Adding a second screen, or folding a device in half also just adds bulk. I like the flat, thin design of tablets like the Xoom and iPad. They fit just fine an any bag I use to carry stuff around in. I mean, do you have some tubed shaped carrying contraption that you need to use to carry a tablet around in? If you do, I guess the S2 is for you.
From a physical standpoint, the only practical use for a folding, dual-screened tablet is when the device reaches a size that can't be carried around easily. If you have a pair of 10-inch screens, a folding design makes sense. But how many of us absolutely need two ten-inch tablet screens? Sure, some graphic designer might use it for content creation, but it seems kind of niche.
The Nintendo DS is an interesting example of a dual-screened device done right, but it's a weird anomaly. It's primarily a gaming device that has a few other features tacked on. The interface was designed specifically for the device, and its scope is far more limited than any tablet running a smart OS. And, it only has one touchscreen and hardware controls, which means that in instances where the touchscreen fails to navigate or control, there's an alternative. Dual-screened tablet devices don't have that luxury.
Ultimately, a single-screened tablet device will handle and function just as well as a dual-screened device for 90 percent of us out there. You can sit and argue and romanticize the things you could do with a dual-screened tablet, but the truth is that, like front-facing cams and 3D screens, they're sexy conceptions of the future that have minimal practical use in our current lives.