It hasn't gotten much attention outside of some Christian conservative and geek blogs, but iOS 7 has fixed the longstanding parental controls webkit hole. I first wrote about this problem back in August 2010, when I was particularly enthused about the benefits of iOS for #1 son's use.
That enthusiasm was muted by years of struggle with adolescence, impulse control, and the webkit access flaw he exploited mercilessly.
Now, with iOS 7, the struggle appears to have ended. With my permission #1 attempted, vigorously, to bypass the new controls. He failed, indeed he has had to sheepishly ask me to grant permissions for webkit holes I didn't know about .
In addition Apple has done some magic to deal with technical issues related to https use that have completely broken parental controls on OS X Mountain Lion. Today Safari on iOS 7 is much more useful for #1 and #2 that it is on Mountain Lion.
iOS 7 is buggy, and does run somewhat slowly on old iPhone 4 hardware, but this one improvement is more than worth the cost.
 Example: In MLB baseball player stats display uses embedded webkit, and so they are a potential avenue to the unfiltered net.
Siri: "Show me pictures of dogs". Shows dogs.
Siri: "Show me pictures of xxxx"....
You have to disable Siri, there are no parental controls there. I wonder sometimes if we need a different kind of IQ testing for #1.