I believe we've asked this question before on Line Out, but technology is ever-changing, and it often evolves faster than we users can keep up. As a consumer of music, I have my own gripes and hypes about some of the more ubiquitous services (the hyper-positive commenting on Soundcloud, or the fact that Bandcamp's Checkout button doesn't automatically open in a new window or tab, thereby shutting off the music that you like so much you decided to buy.
I haven't messed enough with Facebook's feature to decide whether I like it or not as a consumer, and Twitter is an entirely different beast. Also, I have a running theory that rockers use Facebook and heads use Twitter. And are there others out there? I don't even know. Chime in via the comments section to answer an explain/complain.