I take my Kindle everywhere! On cruises and planes, I cut off the wireless-it helps to save on your battery,too. I love to sit on our balcony, watch the ocean and read. This was one of the best investments I've made! Be sure to download your books before you leave home.
A Kindle owner here...and I would go for it. Even if you never use the Whispernet feature while you are onboard, you will certainly enjoy the ability to carry one device for your reading material. My battery usually lasts about 4-5 days when I use it a lot. I keep the wireless off most of the time, unless I'm downloading a book from Amazon. Traveling with the Kindle was the primary reason for my purchase as well. I'd never go back to traveling without it.