I made heavy use of Google Reader, checking it several times daily every day. But I never used the social features—I barely knew about them.
Learning about them now, I think I would have loved them. Most of what I do on social media is share things I find elsewhere on the Internet, sometimes commenting on them. I’ve never found a platform where that kind of behavior was a perfect fit. Reddit comes close, but there’s a lot of overhead on Reddit finding the right community to comment in, and figuring out those communities’ sometimes esoteric rules.