Hi Andrew, FB?
Pros, good for keeping in touch with far flung friends and relatives.
Has a built in messenger so you can chat in real time.
There are loads of local for sale and wanted type groups, plus free stuff that is no longer wanted ( like garden machinery that doesn't work!!!) and "does anyone want to come and take this away" type ads.
Great way to find a Russian bride, whether you want one or not!
Cons
It IS a time thief
The front end interface is very clunky, and not at all intuitive.
You do have to be aware that people who suddenly want to be your "friend", even though they may live on the other side of the world, may have an ulterior motive.
TBH I don't find the advertising that intrusive, and the spam is easy to deal with. One of the great things is you get email notification of people in your circle who post to facebook, so you know who has posted what, without opening it, and can choose to ignore it.
I use it, but not regularly. Give it a try, and if you don't like it, dump it!
Phil