One thing that I miss from Google Reader is having an easily accessible list of items that have been marked read recently.
I found this especially useful in some cases of browser crashes which happen shortly after I select a new item to read where I may not have looked closely enough at it to be able to easily return after restarting the browser. This would be even more useful with NewsBlur, since browser crashes seem to be more frequent (I suspect this is largely due to problems at content sites rather than with NewsBlur itself).