DISCLAIMER: All views are considered my own and you should not draw any conclusions on associates.
since last month and IT IS SO FREAKING USEFUL! My gawd, why haven't I used this before? The most useful aspect about it is the fact it provides two keys "j"/"k" to navigate through the news items, so you are basically skimming for interesting things with no friction! You can mark all as read for certain rss feeds like hacker news for example as there is no way I'm going to read every item that appears in that feed. I don't think I've gone to the websites of these sites since I've used Google reader with exception to hacker news (it's unique with the popular posts factor which is not like its feed). Wow, just wow!
I started using it once I felt that keeping up with the sites I like and programming would conflict and it is the best choice I've made for focusing on my project year. Really amazing product that makes no money though, haha. Probably will create my own "Google Reader" as I want to add some machine learning/nlp techniques to help me with handling overlapping stories between feeds. Marking them as read, hiding similar stories, or some other way.