If you've seen other HBO-produced original shows like The Sopranos, Deadwood, Rome, and Band of Brothers, I think you'll know that there's nothing at all to worry about regarding censoring lots of things like language, sex, and violence.

What seems sure to happen is that some of the younger characters will be made a bit older, according David Benioff and Dan Weiss, for several reasons. George has previously said that he would have added a couple of years to the ages of the characters if he could, but circumstances don't allow him to do that; but it's not an issue for the HBO production. Another reason would have to do with the very pragmatic issue that there are strict rules for the safety of child actors, including limits on how many hours they can work in a day, which would be awkward for a production if it has many minors in significant roles. And with somewhat older characters, certain mature scenes in the books may be able to play out on screen without any concerns.