Amazon described the Paperwhite and Paperwhite 3G as being "the most advanced e-reader ever constructed," offering 62 percent more pixels, 25 percent higher contrast, a patented built-in front light, eight weeks of battery life, and a slimmer design. The Nook model, a front-lit e-reader that Barnes & Noble launched in the spring, will now cost $119, down $20. The entry-level price of the Paperwhite is $119.

'Exceeded Our Expectations'

The Paperwhite's lighted, high-contrast screen is one of its most touted features, allowing reading in any lighting conditions, and the 3G version provides free 3G service. The fonts are specially designed for the high-resolution display, and a new Time to Read feature lets users know how long it will take to finish a chapter or book.

The company said in a statement that "pre-orders have far exceeded our expectations." Reviewers have been falling all over themselves in praise of the new device. NBC News, for instance, called the Paperwhite "the new king of e-readers," and Time Magazine called it "the best e-reader yet."

Some reviewers have praised the Paperwhite over the Nook with GlowLight because of a more uniform screen lighting. The GlowLight was the first E Ink-based e-book reader with edge lighting, a design now adopted and improved upon by Amazon.

But the Paperwhite includes what Amazon calls Special Offers -- that is, ads -- unless you choose to pay an additional $20. Barnes & Noble noted in the announcement of its price drop that its e-readers are ad-less.

Like a Dickens Character

Some reviewers have also pointed out that the Paperwhite does not feature hardware page turn buttons, there's no headphone jack for listening to audiobooks or music, and there's no AC adapter with the model -- only a USB cable. An optional AC adapter is available for another $19.99.

But the display is getting raves, which some reviewers are comparing to reading on paper, and could help to keep e-readers around as a category even as tablets get cheaper and smartphones get larger. The six-inch screen in the Paperwhite, housed in the 6.7 inch by 4.6 inch body, is also getting comparisons to the hand-comfort of a paperback.

Ross Rubin, principle analyst for Reticle Research, noted that a friend of his described the Kindle Paperwhite name as "sounding like a character in Dickens." If so, it's one of those Dickens characters who's undergone a transformation.

Rubin recalled the "frustration of the early days of e-readers," with displays whose contrast was gray on white instead of the black on white that readers of paper-based books enjoy.

He added that, while e-readers the size of the Paperwhite will appeal to consumers, it is likely to find only limited applications in businesses, such as for small manuals, because larger manuals, and documentation accompanied by apps , will require the larger displays and power of tablets and laptops.