This subject is generating all sorts of conversation (mostly hate) in the Steam communities, so I figured I'd have my rant here and just link it there, rather than having to type this multiple times to respond to the absurd amount of topics on it. There is even a petition out to try and 'force?' Valve to change how Family Sharing works.
So, to kick things off, here's how things currently stand. You authorize another computer (hopefully without giving someone else your account info) and they log in and make a new profile. They download and install the games they want to play, and viola, magic happens. That's not quite right, however. Should the main account holder ever log in, it kicks off the other user, so you can only share with one person at a time, and it's not really sharing because if you log in, they go bye bye. Additionally, Steam has a hard limit on authorizations to other computers set at 10 due to SteamGuard and SG has to be active to make use of this feature.
Right now, this is all in beta and only a thousand people have access to this to try it out, but the complaints have been flying like crazy from the hundreds of thousands of people waiting on this feature to go live or get access to the beta.
In regards to 10 computers...I do.... I could fill up the authorized slots for this feature single-handedly, leaving no room for friends or family to join outside of my household....my wife would be happy...if she didn't already have her own Steam account.
There is some degree of logic in how Steam is attempting to do this, and at the same time, it is, indeed, a terrible idea that really should have been thought out more solidly. Most steam users are fairly casual and only log in an average of 4 hours a day. Additionally, you can't really make use of your steam account while you are at work or school, in most cases, so this leaves hours of dead time with the account not in use.
While you may work 1st shift, say a friend or family member is either too young to work or works a different shift and wants something to do other than sit around all day. The last thing you want is them logging in and mucking up your save files. You'd come home to things like 'I beat the next boss for you, big brother' only to find out they sold all your epic equipment that you weren't high enough level to equip yet in order to buy stuff in level to do it, or worse, your save file has been completely changed and you can't fix it for some reason. (Yes, I've had this happen before)
Giving them their own profile on your account and their own saves will save you from headaches of that sort. When you get home, you boot them off to go watch cartoons or do their homework and go back to shooting random people online, or whatever it is you do with your steam account normally.
For heavy users like the rest of us, this becomes highly inconvenient, however. My brother doesn't live with me, I work from home and really have nothing better to do with my time than play games while idling about, so the sharing in its current format is rather pointless. I already have my account logged in from most of my computers in offline mode so that my wife and/or friends can play together. As a note, multiplayer still works fine for games that don't require cdkey authentication or rely on steam for setting up multiplayer matches and the sort. Additionally, if you aren't logged into whatever 3rd party application is necessary for a game, that other computer can be, even while Steam is offline. Either way, this feature is pointless for people who are already set up like I am.
If you really need multiple copies of a game, you can actually create another account on Steam using a different email. I buy a lot of the game bundles from various websites, and this leads to the inevitability of having multiple copies of the same game. Of course I don't want to waste my money (as little as was spent...ahem) and have a copy of a game dangling out in limbo, so I put it on my other account. Now when a friend comes over and wants to play something but doesn't have a copy, I just sit them on another computer on another account and bam, multiplayer can ensue without worry about anything not working because of the game being on the same account. When sharing goes live, of course these other accounts could be setup for sharing as well.
Some people will argue that I could give these extra copies to other people (which I do for games that I have more than 3 keys for), but that restricts me to only being able to play that game with that one friend. If I have multiple copies myself, I can guarantee a multiplayer experience on a computer that is able to handle it properly to any of my friends that visit. Wow, that was a tangent, but somewhat related.
The current debate is whether or not any of this will serve any purpose other than frustrating the masses. If you have multiple accounts that are decently seeded with games, there shouldn't really be an issue. If you are one of the many people who is rarely home enough to enjoy your relative Steamy-ness, then rejoice that SOMEONE can enjoy it, even if it isn't you. Perhaps they'll find a solution to that puzzle you've been trying to figure out for months...or you can share in your sadness and frustration for being stuck at the same part of the game.
The general masses shouldn't really have a whole lot of ground for complaints, but heavier users like myself with a huge financial investment into Steam will find this very lackluster and disappointing. What's your stake on things? Let me know in the comments section!