If possible, I love my Kindle even more than I did when I reviewed it a few weeks ago. I've got about 50 books on it, and I love always having something with me to read. I also love the ease of using it one handed, and checking my email from anywhere. As far as I'm concerned, it's better than a book. The biggest downsides are that not everything I want to read is on it yet, and conversely, that it's awful easy to spend a hell of a lot of money browsing. But there's so much cheap content from the public domain that this is not a huge issue.
Arnold Kling, however, has a different experience:
It turns out that my reading style is to scan. Sometimes I'll be in the third chapter of a book and start asking myself what the author is getting at. So I'll flip to the conclusion. Or I'll jump ahead to what I think is a more important chapter. Although one can use the Kindle that way, it takes a lot more thought and effort than with a paper book.
My main concern continues to be with what is available on the Kindle. The typical semi-academic nonfiction that I read tends to be unavailable. My guess is that if I stick with the Kindle it will skew my reading in the direction of more popular nonfiction.
I'm not the first one to say this, but it's probably bad to try to replicate an older media experience using a new technology. Instead, if a new device is going to have real impact, it has to be adapted in unexpected ways. For that purpose, the proprietary Kindle format and the closed operating system are its most serious flaws. If it could be hacked, I could imagine it being used for email or blogging. Or it might become a vehicle for new scholarly journals, or cheaper textbooks.
But as a closed system, you have to compare it to book technology. It is easier to purchase, carry, and store books on the Kindle. But it is harder to read them.
I find it easier to read than a book, because it's so little work to turn the pages. On the other hand, I tend to read straight through, rather than paging forward. I find it easy enough to go to the next chapter using the table of contents menu choice that this hasn't even registered on my list of potential annoyances.
I think the usefulness depends a lot on how you read. If you read a lot of books, it's great; if you only read a few, it's not worth the money. If you travel, it's vital; if you rarely leave home, it's probably not. And if you're a plodder who starts and goes straight through, it's probably better than if you like to flip. Still, most people I know who have them, love them.