My wife got me a Kindle for my birthday last April. I was pretty suspicious of it. But I've read two novels on it. I've also read several other books the old fashioned way since getting the Kindle. I'll continue to do both, I imagine.
The Kindle's not at all uncomfortable, you get used to it, and it's just a different experience--not a bad one. It's awfully convenient to carry around. The whole fam's going traveling later this summer and I'm going to be happy to take the Kindle. And you CAN take "margin notes" with it, and finding them is easy. You can look up words without losing your place.
If you find yourself blanking on who some marginal character is, just type the character's name in the space provided. You get a list of references. Just click and you can move temporarily back to the character's first appearance. There's all sorts of neat tricks you can do.
I don't think it will ever replace printed books for me. I still like to own books, real books, on the arts. But it's got a role. And if you do buy books, but don't care about storing them on your shelves, the e-books are cheap compared to the real thing.