Clayton Christensen (The Innovator's Dilemma and The Innovator's Prescription) spends a lot of time discussing how disruptive technologies work. The key observation is that a disruptive technology is never introduced in the same model as the incumbent technology that it is disrupting and that it never delivers the full experience of the technology it is disrupting. In other words it is a different business with a different customer base.
So looking at the Kindle from Amazon, it absolutely scores in both of those dimensions. It isn't the incumbent publishing industry and distribution model industries, and it doesn't do some things as well as books. So the serious bibliophiles (me among them) will tend not to see its advantages. However what it does is to enable a whole new class of readers, make certain kinds of reading more doable, and to massively reduce distribution costs - and thus end user costs.
I have had my hands on a V1 Kindle and this is what I thought about it.
It works as advertised - the screen and ink are gorgeous.
Downloads are easy and cheap
It is pretty light with a convenient physical form factor
It is good enough for handling work documents (word/pdf as long as black and white).
You can whip it out anywhere and quickly get to find your place.
In the Kindle 2, there appears to be a builtin dictionary (there may be in the 1 as well, but I didn't try it)
You can't use it while waiting for takeoff (I had my hand slapped for that one!)
The page size is just too small - even with the small font I can't get enough on a page.
The page size means I am page turning like Keith Moon on speed (for those who are wondering, Keith Moon was the manic drummer for "The Who".
Pagination with diagrams gets all messed up. Again a function of screen size.
Book marking is clumsy
Having multiple books open at marked places and hopping between them is clumsy (especially annoying when attempting to learn a new language).
In the cons section, it really all comes down to screen size/format. There is wide variance in the size of printed books. My coffee table History of the America's Cup, for instance is a full 18" wide when opened, with full color photographs that spread across the 2 pages. That simply isn't a Kindle opportunity. Come to think of it, I don't think there is a "coffee table Kindle" just yet!
Where it is a bit more serious for me is in the reading of text books/tutorials. The Kindle does standard novels in paperback form factors very well, but when trying to use it to render a text book (in this case a book entitled RailsSpace) and try to learn from it there simply wasn't a hope.
So for me, adding a Kindle will add to my burden, not detract from it. I'll carry it for the novels, but will still carry my collection of text books.