There's already some great answers here, and I mostly agree. The Kindle is well worth the price. I own an older Ebookwise 1150 ereader, and while I love it, the fonts show strong pixelation. The Kindle is a vast improvement. The screen quality is awesome. Unless you actually hold one in your hands and see the print on it, it's not possible to comprehend how much better it is than computer screens.
I'm usually working on at least one book, usually more, on any single day. Having them all in one device is very convenient.
I can (and do) spend a lot of time reading on other devices, but for pleasure, ease, and convenience, Kindle is worth the money to me. And the battery power? I can usually get about 3 weeks on my Kindle, then I recharge just to keep it topped up. And that's one of the older Kindles, not the newer models that work even better!