I do but I feel it's long overdue for replacement. I've been working on a new protocol that includes timestamp filtering, real-time notifications, and optional things like 'likes' and 'comments'. I use it everyday and I load it with content from RSS feeds. Not ready for sharesies yet though
I see bots trying to generate feeds in my access logs. Some of them are coded very poorly, ignore cache-controls, re-check articles every 30 seconds indefinitely. So it would seem they are still used. daily-digest/1.0 (Article Reader) is the worst one I have seen thus far.