When Restrictions was first introduced, there was a lot of trash talk that it is ridiculously simple to break. All you had to do was go to Settings > General > Reset > Reset All Settings. At least that is the claim.
Well, turns out it is not so easy.
Try the sequence above and you will be asked for the Restrictions passcode. You cannot reset the device without entering the passcode, which is pretty good protection. Now if someone is desperate enough to try and enter all possible combinations of 4 digit passcodes, you probably have a more serious problem than you think, and it has nothing to do with the iPhone and passcodes!