Oh yeah... "Restrictions" are a norm for parents that have iPhones or iPads.
Why you may ask... My 3 years old loves playing games, and I usually have $50-100 on my iTunes account to purchase apps or songs. One day, after updating a few apps on my phone (requires my apple password), I handed my phone over to my little guy. He bought about $20 worth of apps. Remember- once you've entered your password for iTunes/App Store, it doesn't prompt you to re-enter it everytime you decide to purchase something else... At least it doesn't for me and I haven't seen where I could change that. I Just restricted it.
You Tube: kids love watching You Tube... and it's not always appropriate (age appropriate).... I'll just leave it at that.