The Old Reader probably not fit for new paradigms of news reading
The Old Reader was originally developed by people upset that Google removed social sharing features from Google Reader. The idea was if Google was going to gut supposedly useful features from Reader, they'd develop their own Reader to preserve those features. Fast forward a couple years and now we have Google about to kill its Reader, and Old Reader isn't quite up to the snuff of replacing it.
Old Reader does work in that you can import your OPML file full of feed subscriptions, and use it to read news. It also has that all-important social sharing functionality. But it lacks a lot of modern features and for me the killer is that you cannot tag posts.
To get started, go to http://theoldreader.com and sign up. You can import an OPML file, which is the "subscriptions.xml" file which Google will provide when you export your Reader information. When I imported my subscriptions, I was informed that it would not process the import right away because of the large number of people wishing to use Old Reader. It took a couple weeks to get the import processed.
The user interface is familiar, with a subscription list on the left, and news item display taking up the bulk of the screen. Click on a subscription and you're shown the items in that subscription.
It supports toggling between a list view and "full view" that shows the full content of each feed entry.
The behavior of the user interface is fairly good and fast. It will feel familiar to anybody familiar to other news reader applications.
However, unlike many other news reader applications the actions you can take with each news item are very limited. You can "Like" an item, you can "Mark it as Unread", and you can "Share" the item. The sharing feature works ONLY within the Old Reader community. There is zero ability to share an item out to other communities like Facebook or Twitter. There is no integration with apps like Instapaper. There is no ability to add tags to an item.
I have to give this both thumbs down.