Just a quick tip for anyone getting a new iOS device (iPad, iPhone, iPod Touch) for Christmas:
Everyone in a single family should use the same iTunes Store account (Settings -> iTunes and App Stores), but each individual should have their own iCloud account (Settings -> iCloud).
That ensures that you all get to share the same media (videos, songs and apps), but the separated iCloud accounts lets you each have your own contacts lists, calendars, reminders, etc.
Many people make the mistake of all signing into the same iCloud account and quickly find out that their contacts and calendars, etc., all sync up and make a mess.
The harder problem is if the device is for a child, since the minimum age for iCloud accounts is 13. I can't find any recommendations for this on the net, so my best guess is to lock down the phone with restrictions, limit Safari, iTunes, iBookstore, installing apps, and explicit language -- all with a passcode that only you know. And don't install YouTube, Google Search, Vimeo, and any other video- or web-searching apps. If you want them to be able to watch videos, consider Netflix' "Just for kids", or WeetWoo (an app that's basically a directory of clean YouTube videos). You'll want to monitor your kids carefully too, remember my post about allowing a crippled mind to poison itself? Lots of mental and emotional poison on the internet, and people can be pretty awful about discerning it, especially kids.