Kindle pros

increase the size of text (for visual impairment)
not as heavy as book (for people with hand and wrist pain)
doesn't take up space on shelves as a load of books does
less to dust too
can read in the dark
good carbon footprint re trees

Kindle cons

initial cost
running cost (batteries)
bad carbon footprint re plastic and batteries
can't take it into bath (well I wouldn't)

All being said, I would rather have the book than the fancy piece of tech. Just feels so right to curl up on sofa on cold grey day and read, read, read. The weight of the book, the turning of the pages, and when you are really engrossed and don't want it to end the dread as the unread side of the book gets smaller and smaller.

Can't experience that with a Kindle.