The concept of the smart display itself is not bad. The execution of that concept, which is embodied in Microsoft's Smart Display software, was terrible. In private, hardware manufacturers acknowledged the limitations of the software and tried their best to work with it, but even those best efforts were not enough to blunt the Goodwins pen.
Microsoft blames the failure of the Smart Display experiment on the state of the LCD market, which given the ever-plummeting prices of LCD monitors is a bit like Britney Spears saying she'd have stayed married if it wasn't for the divorce rate. No, the problem with smart displays always lay in the licensing.
Unlike tablet PCs, which are a self-contained computer, smart displays have no local storage and can only be used to interact with a computer located elsewhere.
When undocked, they use integrated 802.11b and Microsoft's Remote Desktop Protocol (RDP), a feature found in Windows XP Professional, to connect to the base computer. The docking station has a USB connector to the display and a VGA connection to the PC, allowing it to function as an ordinary monitor.
The displays came in two types: those which could be used as either a desktop monitor or a portable tablet, and those which only functioned as a remote terminal. ViewSonic's 15-inch Airpanel V150, which is still available, doubles as a monitor and a remote terminal, while the 10.4-inch Airpanel V110 can only be used remotely.
The trouble came when using the displays in this remote capacity. When the smart display was controlling the computer, the base computer was locked and could not be used by another person.