The new design is obviously optimized for touchscreen use (where big targets are helpful), but Microsoft is also imposing this style on its traditional PC users because all of Windows 8 is permeated by the tablet sensibility.

How well does this work for real users performing real tasks? To find out, we invited 12 experienced PC users to test Windows 8 on both regular computers and Microsoft’s new Surface RT tablets.

via Windows 8 — Disappointing Usability for Both Novice & Power Users Jakob Nielsen’s Alertbox.

The underlying problem is the idea of recycling a single software UI for two very different classes of hardware devices. It would have been much better to have two different designs: one for mobile and tablets, and one for the PC.