What about in-app purchases? Are those shared yet?
no, which is daft surely.
but the biggie for me is iTunes match
plus a more understandable but still annoying one is accounts from other countries. we have always used my account for portuguese iTunes, for all purchases, and my wife has a uk account without a card attached, for things like bbc iplayer, and other uk only apps.
i had to convert her account to a portuguese one to add it to family sharing, and having realised that theres no benefit (to me) of family sharing ill convert it back.
i think for kids, family sharing sounds great. it makes it easy for kids to buy stuff whilst protecting the adults, so its much better than using different logins.
for adults who both have lots of purchases before they got together, its much easier than swapping logins, but only if you now want to use the same payment card, which a lot of people won't.
for everyone else, if you haven't got iTunes match then its going to sound like a good idea, but not actually benefit you. you could just as easily login as them for 5 mins and download their apps, and this means you still get their in app purchases, and can still purchase separately. if you now want to purchase together then just use one login from now on for buying, and the other persons login only when you want any of their previous purchases.
and if you have iTunes match its a no go.
we are back to the old fashioned idea, my mac, iPad and phone are logged in as me for everything, and my wife as her for iCloud and me for iTunes. works great.