The Kindle's display is nearly as readable as paper, the only issue is a slight glossiness.
It's about the same size and lighter than the paperback I just finished reading, and much lighter than the large number of books it can contain. Finally, I'll be able to take a Neal Stephenson book on vacation!
You can read the Kindle with it sitting in your lap without holding the book to keep it open and positioned.
The keyboard below the screen is great for reading in bed, because the Kindle can sink into the comforter without obscuring any text.
The page is always flat, there's no curve as the page meets the binding. You don't have to fight with the book to get a good view of the entire page even when you're near either end of a long book.
The shopping experience is awesome. I really like that it doesn't require a computer and is very fast for downloading purchased content. Finish a book, buy a book, keep reading.
The cover is really important, and makes the experience of holding and using the Kindle better.
Having a dictionary instantly available, even when you're away from home, is a really great addition to the reading experience.
You can change the font size from pretty small to pretty large, which should be a boon to a wide spectrum of users who want fonts size to suit their taste and eyesight.
Kindle is uncomfortable to hold in left hand by itself. To get it to easily rest in a stable position, the lower left corner of the Kindle digs into my palm and gets uncomfortable in just a couple of minutes.
The cover attachment seems flaky, but is working well so far. I feel like the catch mechanism isn't very secure and will likely loosen up or wear slightly and stop working. Time will tell.
The screen flash when changing pages is distracting, as is the slight delay. The delay is noticeable, but not annoying. I expect people will get used to the flash.
The power and wireless switches are cheap-feeling sliders on the back of the book, which is a real pain to get at when in its case. You don't need to mess with the wireless switch that often, but I feel like I should turn the book off whenever I put it down for more than a few minutes. Should I pop it out of the case to get at the power switch or try to snake my finger between the Kindle and the case without detaching the flaky little catch? It's an annoyance every time I put the book down.
Newspapers don't work on the Kindle. First off, newspapers are not a text-only medium but the Kindle is largely a text-only device. That's fine for novels, but terrible for newspapers. I tried a sample issue of the Seattle Times and it was horrible. I would really like to stop consuming paper by the pound, but newspapers need photos, comics, crossword puzzles and non-linear browsing. I'm not much of a sports fan, so I spend about one second looking at the front page of the sports section to see if there's some new hope for the Mariners then move on. In the Kindle edition, five of the eleven pages in the table of contents were sports headlines. The Kindle edition of the Seattle Times is just a flattened text-only subset of their web site. I'll keep recycling the paper for now.
The last electronic eBook I tried was The Rocket eBook which required the use of (bad) software on your computer, and the content you bought was tied to one device. If you broke or lost the device, your content was also lost. Even with those annoyances (with a device that was larger, heavier, and had a less advanced display), I liked the Rocket eBook for reading on vacation and would have kept using it if the product hadn't died. The Kindle has solved the Rocket eBook's most obvious problems and has really moved the electronic book technology forward.
Still the digital rights management (DRM) issues make the Kindle books a lot different from a traditional book. You can't loan or resell content and your content is only available as long as Amazon keeps supporting the content and device. If you buy a book and the bookstore goes out of business or stops selling sci-fi paperbacks, you still own the book. My wife and I read a lot of the same books, so now we have to buy two copies if we both want to read it on our own Kindle? Swapping Kindles doesn't work: if you finish one book and start another, you've effectively glued those two books together -- you can't pass the book you've finished to the other person without also giving up the one you're now reading.
The Kindle books seem to be priced lower than the price of the corresponding paper book, whether it's hard cover or paperback. That sounds good until you realize you're getting a lot less than what you get when you buy a book.
Amazon could improve the proposition by making it possible to transfer a book from one account to another for a small charge, like 50 cents or a dollar. That way, when I'm done reading a book, I can transfer it to my wife's account, or I can pass it on to a friend, or even sell it. Something like this would give users a better sense of owning what they buy, and at the same time give Amazon and the publishers a stream of revenue when books change hands.