I think Facebook began to go downhill when it introduced "apps" - third-party services of dubious usefulness that tended to be fragmented very often duplicated each other. And it looks as though this is going to get worse.
Facebook Changes Again: Everything You Need To Know:
Facebook apps need only ask permission once to share stories on your behalf. Although not as big a deal as the Timeline, this tweak may be one of the more controversial. Previously, apps had to ask every time they shared information about you in your profile. Now, the first time you authorize the app, it will tell you what it’s going to share about you. If you’re cool with that, the app never has to ask you again.
And that is why, if anyone invites me to something on Facebook, and it asks for access to information about my friends, I back out as quickly as possible.
The last one that caught me like that was a thing called "Branch Out", which at first sight looked a bit like Linked-In.
If you joined, it asked which of your friends you would like to work with in various things. I went through it, thinking it might provide some useful, or at least interesting information at the end of this. It didn't.
Instead, it spammed my friends with a thing on their Facebook "wall" saying that I had said something about them in "Branch Out". But if they went to "Branch Out" they would never find out what I was alleged to have said about them -- they would just be asked to answer a similar series of questions, the sole purpose of which was to collect information so that their friends could be spammed in turn.
In other words, the whole "Branch out" thing is a scam to collect information to spam people. And so it is with a lot of Facebook apps.
If you are one of my Facebook friends, you'll probably see something like this:
Steve Hayes is using BranchOut on Facebook | Facebook.
14 minutes ago
Actually I was trying to see if there is any way of opting out or resigning from "Branch out". There doesn't seem to be.
I'm always presented with several "apps" relating to family history and genealogy, which are interests of mine. Two of the most insidious are MyHeritage and Geni.com. I actually encountered both outside of Facebook, but they too are traps for the unwary. You can see my criticisms of MyHeritage here, and Geni.com here.
I like Facebook for keeping in touch with people I know -- friends and family, especially those who are far away or whom I havent seen for a long time. It's useful for making contact with long-lost friends and acquaintances or recently-discovered members of one's extended family. It's good for seeing what people are up to. But that's about it.