I like tablets (aka slate computers), but there are barriers to their success.
The inclusion of a keyboard in the photo above highlights the biggest problem for a slate device: Text entry. A slate works well if you're using it to browse the web, or read e-books (even Overland Journal, someday), or view Youtube videos, or even to run some custom application like recording a patient visit to a medical office. But a slate fails for general computing. It's just not as fast or accurate for text entry.
There's hope for slates. Some slates talk about having a handwriting recognition application, or even voice recognition. And on-screen keyboards are getting better. The iPhone, for example, analyzes the word (maybe the preceding several words) you're typing to help minimize mistakes with the next letters. But at the moment there's no substitute for a real keyboard for computing that includes content creation.
Then there's the problem of using a slate while standing up. If you have to set the slate down on a table, or even sit and balance it on your knee, then you might as well be using a laptop with a real keyboard. To get maximum value from a slate, it has to be small and light enough to comfortably use it while standing.
What advantage does a slate have over a "convertible" laptop ( a conventional laptop with a screen that rotates 180* and lays down to cover the keyboard) ? The convertible laptop looks to be able to do everything a slate can do, with the advantage of having a keyboard available when you need it.
Laptops routinely weigh less than 3.5 lbs today, even ones with convertible screens. Check out the Gigabyte T1028X, for example.
Another challenge for a slate computer is readability of the screen. A portable computer will be used in bright direct light and sunlight, areas where conventional LCD screens are hard to read. The new e-Ink and PixelQi screens look good and use less power, but they are grayscale, not color. Some day we'll have the answer, but not today.
Then there's the matter of boot-up speed. Would you want to carry a slate that takes 60 seconds to boot up? That's the current speed of devices running Mac OS/X or Windows 7. There are stripped-down unix solutions, most notably Google Chrome, that boot in a couple of seconds. But they don't run the software that people use for general computing (text editing, spreadsheet, photo manipulation, etc). Some current computers can run for a day in sleep mode, so maybe the answer is a design that you never turn completely off.
Would you buy a slate if it cost 50% more than a laptop with similar performance? The high volume of production for laptops keeps their price low, while a slate will certainly be a low volume item, at least at first.
Chip Haven
