I use goodreads quite a bit. I use it of course to log all my reads. With many shelves and star ratings. Sometimes I write a review. I have lots of shelves on there for stuff coming up, etc.
I mostly follow folks that read stuff I like reading. So when I look at a book, I only ever have to look at the reviews and ratings of readers I follow or have friended. After a while I know what they like or not like and so on. Huge help for finding stuff to read. Also, I can compare my shelves with others and see how good of a match we are. It gives you a percentage and takes in account star ratings. Again, huge help finding folks to follow.
After a while this creates a goodreads that is very tailored to my tastes and wants. So my home page feed is targeted. I get to find out about new books coming out in my genres from authors I like or will like. I get entertained by the funny book stuff some folks are posting. I get emails once a week on new releases on authors I have on my shelves.
Also the recommendations are now spot on for me. The more I rate, the better they get. Those recs are actually better right from my kindle for some reason. Easier to navigate too, filterable by genres one likes.
I hate facebook and I don't do social media stuff at all. But I love goodreads as its all about books. And I am all about reading.