The Kindle is great for books that are just a bag of words, but falls short for anything with important visuals.
I’ve really enjoyed reading on my Kindle over the past year. You can’t beat it for dragging a bunch of books with you on vacation or for reading by the poolside. That said, I don’t use it to read anything technical with diagrams or source code listings. I certainly wouldn’t use it to read anything like Tufte, which is exactly why his books aren’t available on the Kindle. Where the Kindle shines is with pop-science books like Freakonomics and Star Wars novels1.
If you love books and reading, the Kindle is a nice addition to your bibliophilic habit, but it’s no replacement for a well-chosen and varied library.
1 Did I say that out loud? Crap.