First, how many places are there to set your account? There are 5! If you separate them, make sure to do so every place you intend to do so.
Update on 1/6/14 - TidBITS linked to an article about Family Sharing that is important from someone quitting family sharing: http://macsparky.com/blog/2015/1/quitting-family-sharing
-- iTunes match is not shared, from what I can tell. I was told I could continue to share music content, but this is not the whole truth. I was sharing via iTunes Match. The separate ID does not allow for this.
What are the implications?
- This separates iCloud backups of ios devices!
- This separates photostreams for each person - you lose the ability to stream photos with any devices on a separate iCloud account
- It enables easy setup and sharing of:
- a shared photo album all family members may publish to when they choose. This typically causes an alert just like with other shared photo albums.
- a family calendar
- a family reminder "group"
- If you use one account, you can keep a shared photostream and iCloud storage account for backups, but then could be sharing contacts, calendars, documents, and more. This can be problematic.
- iTunes, App Store, iBooks bookstore
- App purchases are available to all family members (although I read that there is an ability to hide purchases. I have not explored this)
- In app purchases are only available per account and are not family-shareable
- iTunes Match is no longer shared. If you share music via iTunes match, another account will need to be purchased. I believe it will also need to be "primed" with all of your music. This looks like a bit of a mess!
- This needs to be separate for each person to be able to use sms messages on their mac linked to their iPhone.
- This needs to be separate for each person to be able to use their cellular phone linked with their mac to make/receive phone calls.
With shared messages and facetime, wackiness such as receiving all family texts on one computer and/or one iPhone can be accomplished!
- Separation means a family competition can begin! Also, separate friend lists can be had.
I think messages and facetime are close to being synonymous. I suspect in some future version of iOS and Yosemite, they will no longer be separate. In fact, I suspect that this complexity of 5 different places to use an account will be eliminated and shrink to one account at some point.
- I think it is clear that each person using a separate AppleID for Messages, Facetime, and Gamecenter always makes sense. If I have that wrong, and you disagree, please tell me.
- This one Graham Spencer of MacStories strongly recommends be separate (see link below).
- This is very hard for families used to having a completely shared photostream; auto-sharing is lost.
- It also means if you have one purchased larger iCloud storage capability, it is no longer shared for backups.
- It lets each user have their own documents, calendar, contacts, while enabling easy sharing of the same with family members. This makes it seem pretty necessary.
- If you use 2-factor authentication, and you should, your family members need to type this in when purchases are made. This means having it separate is probably a necessary idea. However, you lose sharing in-app purchases, such as true app-activation in some cases.
- When family members split from your family group at some future date, they keep their purchases. What else does it mean? This is not clear.
I really do hope Apple can eliminate this kind of complexity for its users.
Here are a few articles for reference which can really help as well: