I don't want to rant about my personal experience only. Fortunately, Jacob Nielsen has posted some results from a user testing with 12 experienced PC users to test Windows 8 on both regular computers and Microsoft's new Surface RT tablets. I cannot agree more with his conclusion: "Windows 8 UX: Weak on Tablets, Terrible for PCs... Summary: Hidden features, reduced discoverability, cognitive overhead from dual environments, and reduced power from a single-window UI and low information density. Too bad."
There are three different kinds of demands or loads that you can make on a person: cognitive, visual, and motor. Looking at something or to find something on a screen (visual load) uses up more mental resources than simply ask someone to press a button or move a mouse (motor load); asking a user to think or remember or even do a mental calculation (cognitive load) is the most mental resource intensive task, which is why "Don't make me think" and the formula for Fitt's Law.
- Auto-hide is terrible for new user
- Avoid switching input devices
The basic problem here is switching user input devices, no matter keyboard to mouse, or touch-screen to keyboard, this is exactly the type of motor load to avoid in Human Factor terminology. Without the start button, the most basic operation as running a program could involve switching between two devices, namely, press windows key, click on the start screen.
I guess what we could all learn from this is, it's not easy to get all different user interfaces work well together, people are still fighting over keyboard-based command-line and mouse/trackpad-based point-click preferences. If not done right, adding touch-screen could be disastrous.