I found the Kindle's design finger-friendly; the buttons flowed logically as I navigated the device. I also liked the scroll bar/select wheel combination, whereby you scroll to menu options by using the wheel, and then push the wheel in to select options.
You can also push the wheel in to call up a context-sensitive pop-up menu. For example, when you're shopping in the Amazon store, the menu offers to take you to Home, the Kindle store, Top Sellers, New & Noteworthy, Recommended for You, and 'Save for Later' items. I particularly liked that last option: I could pick things I stumbled on in the course of browsing, and bookmark them to find them again before proceeding with another purchase.
When you're at the Kindle's Home screen, the pop-up menu offers to send you to the Kindle store, check for new items, change the device settings, and manage content, moving items from the Kindle's 180MB of user-accessible memory to an SD Card and back again.
This menu also offers "experimental prototypes" that include a basic, text-friendly Web browser and a background MP3-music player. Curiously, Amazon presented the latter at launch as a feature, not a prototype.
While reading, you can use the Kindle's select wheel to highlight a passage or choose where to make an annotation. You can then e-mail a highlight to a friend or access your notes--stored as text files--via the Kindle's USB connection.
A Few Quibbles
Sometimes the Kindle was slow, as the device lagged behind my button presses. In those cases I'd overshoot the menu or options entirely. Still more times I encountered a lag or a flickering fade-in effect as I transitioned among menus and changed pages. The lag wasn't so onerous that I couldn't use the device, but it was annoying--and it became very pronounced when I tried to virtually flip ahead several pages at a time.
The screen has a gray, indistinct quality that resembles the appearance of newspaper. The monochrome screen supports four levels of grayscale. I had no issues reading the display under a multitude of circumstances, including in bright lighting and while riding a Long Island Railroad train. Since the display lacks a backlight, however, the surface wasn't readable in dim lighting.
The text was mostly clear, though a few characters had jaggies. A button on the keyboard lets you switch among six different font sizes. One important note for those who require large-print text: The biggest size is actually larger than the text I saw in a large-print book I had on hand.
The navigation software is fairly straightforward, but occasionally it doesn't do what you'd expect. For example, the Home screen shows you the user guide and your content. You can sort that content by books or periodicals, or by most recent, the title, or the author. You can't search on these parameters, which is annoying if you're hunting for Harry Potter books but not a set of critical essays on Harry Potter.
Another glitch: After I made a purchase, I could not return to the page I'd last been browsing--incredibly irritating when I was in the midst of 17 pages of search results.