Reading on things like the Kindle Fire or using a cell phone Kindle app at home works well and of course the screen is better, but outside these devices are crap. You spend your time looking for shade just to barely make out the text.
I know that outside of Bournemouth, not many people back home in Blighty might choose to read a book on the beach, but I've heard that one or two do make the perilous cross-channel journey during the summer. So after you've finished eating (or shouting at the waiting staff in English in the vain hope they will understand the universal words "LAGER", "TOMATO SAUCE" or PROPER CHIPS) there is nothing better than sitting on the beach, squinting at a 4" screen.
Naturally over here in the colonies, we prefer to squint at an 7" or 10" screen depending on your wallet size and whether you prefer your books in iTunes or Amazon Cloud format, having just spent an hour shouting at waiting staff who claim to speak English but don't understand the words "bottle", "water" and then bring you crisps instead of chips.