My brother is one of the evil rich, selling software for a mobile tech company. He uses his iPad all the time for business presentations. It can’t replace a laptop if you really need a laptop. There are a lot of people that have laptops than don’t really need them however. i think most of the sailors that worked for me didn’t really need a laptop. They may need one now because so many Navy sites require CAC cards, but if you are just surfing the net and managing your media it is a nice piece of gear.
I bought my son a Kindle for Christmas. He’s a “glow-worm bubble-head”. He loves to read and it’s perfect. Holds a ton of books, last weeks on a charge, and doesn’t take up much of the half a cubic foot of personal storage space you’re alloted on a sub.