I just came across it today, and other than spending time on it that I should have been using for work, I can't express how happy I think I am (I can't be sure until I spend at least a few days weeding out all the things I might hate about it). The greatest thing is that I don't have to save each feed into it's own inflexible folder as with Bloglines and all the other RSS readers I have tried for windows, and it lets me read all my subscriptions in order of date of post, intermingling articles from various sites (Shrook, my favorite for Mac, did what I wanted but unfortunately they don't have a Windows app that I can use while I am at work).
The best thing though, is that Rojo is all-out Web 2.0, and allows me to tag articles and blogs so that I can browse by tag, category, blog, etc... as well as browse other people's tagged blogs and articles without going to technorati or Delicious. And if enough people start using Rojo, or some other app that integrates with it, I would guess the results would be much more satisfying than delicious because it is much more convenient to tag the post right there than it is to save it in delicious.
The one thing I haven't figured out yet, is how to subscribe to all the posts that other people have tagged with a ceratin tag.... but it *must* be possible.