Plusses: you only have to pack one book on your holiday. You can buy a new book at 1 am and it's there instantly, instead of waiting for the library/bookstore to have it in. You can hold it and 'turn' the page one-handed, so perfect for reading with a sleeping baby on the lap. You can buy a cover with an inbuilt light, so perfect for reading at night without disturbing a partner/while breastfeeding (I read all of Game of Thrones during night feeds!).
Minuses: you can buy a new book at 1 am instead of waiting for the library. Err...I guess it would be annoying if you packed it on holiday without the battery cord? (But they take a very basic charger cord, I use the same one as for my phone). Kindles, specifically, lock you into using Amazon, so that's slightly restrictive.
Get a £29 nook and root it to take kindle books.... really easy to do
Also loads of free domain stuff and the nook WILL take books from my library ( kindles wont).
Actually I have a kindle ( old style keyboard ) and a cheap nook. Love them!
Though I don't know what I'll do without the text to speech that the KK has . it might not be perfect having stephen hawkings voice read to you, but if you have to leap in the bath or drive at the crucial moment it can be brilliant ( I can route in through the car speakers!)
I was dubious about getting a Kindle- I love actual books and used the library frequently.
Then I was given one for Christmas.
Apart from the reasons Tortoise gave, I find it fab for popping in my bag to take to appointments (waiting time), on the train/bus. Also as I'm getting a bit old and decrepit my eyesight isn't as good as it was before. Now instead of squinting at a book's small print or searching for my glasses I just increase the font size.
Lots of books are free on kindle. sometimes authors put them on at special reduced prices ie. free or less than £1. Plus you can get a refund for up to 7 days after if you thought the book was horrendous or misdescribed or bought in error. there are websites that tell you daily what kindle books are free. i have read so much more now i have my kindle and have read some brilliant books which were free - admittedly some were total dross. i have the kindle touch and i love it to pieces. I have nearly 300 books on mine.
You can get a warm happy glow at the knowledge that most of the price you pay for an ebook goes directly to the author. Ebooks pay roughly 60-80% of the cover price to the author, while print books pay 10-20%. Ebooks are cheaper than print books anyway, but you also pay far less for delivery, and they are less cumbersome in bulk.