So, you replace an old paper based playbook, with an interactive tool, that can be updated at anytime (never goes out of date). And it allows more that just one thing to be "pushed" to the users - email, notices, video (that is relevant), animations, even discussions could be had either through boards, chat, or video. Seems to be a fairly good step up from the paper based system. Now, the reality, this could have been accomplished without the tablet - via a laptop - with all the same functionality and portability. But, sometimes new and sexy win. Form over function type of thing.
Now, if the NFL can embrace this brave new world, and replace a aging, but time-tested system, what can other do? I believe this is a brave new world. With an almost endless variety of ways to create new and better ways to tackle problems.
Here's some further reading on what the NFL is doing with tablets....Google Search.