I was working on a (now-shuttered) startup in this space. Almost universally people's favorite feature was seeing the live website. I had also built in a reading queue into the application, the idea being that you could do inbox-zero with your feeds if you could process them extremely fast.
I talked to a bunch of largely non-technical RSS power users and discovered that the people who really use RSS readers are subscribed to 1500+ feeds and barely scratch the surface of reading everything in them.
It was really disheartening to discover my fundamental premise was wrong, and at the same time my now-cofounder contacted me with a great idea with a clearly underserved market so I abandoned the solo effort for that.
I think there's a ton of room for innovation in the media reader space, so I wish NewsBlur luck!