First, we already know that this UI is touch-friendly (i.e., will work on multi-touch slates, tablets, and displays), and will work equally well with traditional mouse and keyboard interfaces, supporting keyboard shortcuts just as Windows does today. But I don't think Microsoft has shown off all the possibilities here. I also think that the Start screen will work just fine with today's Media Center remotes and with the Kinect, offering users new (and in the latter case, "Minority Report"–like) ways to interact with gigantic HDTVs in the living room and in public speaking scenarios. It's brilliant.
Second, let's talk user types. Obviously, individuals are going to be all over this UI. But so will business users, since Microsoft will clearly allow corporations to control how (and whether) this UI looks and works, and while onscreen elements are allowed. Are you looking to limit some users to just a handful of work-related apps? Of course you are. And this will make that resulting environment simpler than ever.
What about IT pros and admins? Are you telling me that this new Start screen isn't a killer dashboard for managing the state of your environment? Can't you imagine the screen background changing color (green, yellow or read) based on the environment health? That those tiles wouldn't be ideal surfaces for instant reporting mechanisms, performance graphs, and the like? This isn't just a decent UI for that stuff, it's ideal.
Fourth, as noted above, Microsoft cares about compatibility. And not only iscompatible with exactly the same hardware and software as Windows 7—it will even have exactly the same or lower hardware requirements, Microsoft says—but the familiar Windows desktop is still there, hiding "below" ("alongside"?) the Start screen. (As are all the familiar applications, utilities, and services you know and love today.) The Start screen is additive. It doesn't take anything else away.
And this brings me to what I think is the single biggest point I can make about the Start screen. As its name suggests, the Start screen is not a replacement for the Windows desktop, or the Windows taskbar, but is rather a replacement for ... wait for it ... the Start menu. And it makes sense when you think about it. In Windows 95, Microsoft introduced the Start menu, and the changes we've see in Windows versions since have been largely evolutionary. In fact, the biggest change came in Windows 7, when Microsoft took some of the primary Start menu functionality—shortcuts and program launching—and moved them to the taskbar. With the Start screen, this evolution is complete: Now, instead of doing that stuff from the taskbar, it's done from the full screen.
But it's not just that: Those tiles are far more dynamic and expressive than any taskbar or Start menu icon. So, yes, you could tap the weather tile to launch a weather app, but the tile already displays today's weather plus a three-day forecast, so you probably won't need to. Yes, you could launch email to see whether there are any new mails, but the tile will tell you when one is available. And so on.
With the understanding that there is still so much more to learn about Windows 8—Microsoft promises further revelations all summer and then a BUILD developer show in September—I've already seen enough to be convinced. This new Start screen will work equally well across all the device types on which Windows works, and it will work equally well for all of the company's customer types too. Yes, you can turn it off if you want. But my guess is you won't want to. And if you can just get out of your old way of thinking, and stop being shackled by the way things used to be, I think you'll come around to this notion as well.
Windows 8 has been billed as the biggest change to Windows since Windows 95. And for once, I think, reality matches the hyperbole.