The Kindle is not perfect yet. It could do with some built-in word games such as Hangman, Word Train, Jumble, etc. It could do with an even faster processor. This is the test of true love: I still love it despite its present shortcomings. Here's why.
Before getting my Kindle, I didn't think that the wifi feature was a big deal. I thought it was just as easy to use the USB cable to connect to my computer whenever I wanted to download anything. That was until I found that I could download lots of newspapers and magazines automatically using Calibre (another software), and setting up Calibre to automatically send the content to my Kindle. This is all done through wifi. Of course, with the Kindle you can also pay Amazon to deliver the content to your device, but I quite enjoy doing it myself for free. I have already downloaded Reader's Digest, PCWorld, US & World News Report, The Australian, and Daily Telegraph. There are lots more to choose from: USA Today, BBC, CNN, Business Week, Discover Magazine, Engadget, etc, just to name a few among the hundreds available.
I can always visit the Amazon bookstore through my wifi, choose any book to download, and go back to my reading. A few minutes later, the book is in my Kindle. If it is not a free book, I get to download the first chapter at no charge, with the option to purchase later if I like it. Just for fun, I downloaded the Koran.
As I read a book or an article, I can highlight it, add my own notes, and press two buttons to send it off to my Facebook (or to Twitter). This is particularly useful when you are reading a news article and you want to add your own thoughts to it and publish it in Facebook for all your associates to read. This is almost instant with wifi turned on.
Also thanks to the wifi, I can make use of Amazon's Whispersync to synchronize my reading on any Kindle device, be it on my computer, on my laptop or on the Kindle e-reader. This can be very handy, but I haven't really taken advantage of it yet.
I think Amazon did the right thing to put wifi and 3G into the Kindle. I think Sony made a mistake of not putting wifi into their entry-level e-readers. As for other e-readers in the market, some do have wifi, but they may not have the "ecosystem" (such as mentioned above) for the wifi to be used effectively.