I love my Kindle. I love the comfort of it in my hand, the size of it anywhere I go (with a seemingly unlimited volume of books), and the ability to highlight and notate text.
However, as much as wanted to embrace it for my textbook options, it just didn't work out. Perhaps it's my unique comprehension style, but when I'm drawing from multiple sources, I like to have those sources spread out and evenly visible.
So, consider your learning style and how you like to work (as opposed to casually read) when purchasing your textbooks.