Looks like NewsFire has gone free a la NetNewsWire. I downloaded and played with it for a while, and while it is impressive, I do not plan on switching from NetNewsWire. One nice feature that NewsFire does have is that when a feed (in the left sidebar/column) has no unread articles, NewsFire moves it to the bottom of the list. I would like such feeds to be entirely hidden, as Google Reader does, but this NewsFire feature is at least better than the lack of any such feature in NetNewsWire or other readers.
If you are looking for other free options for a Mac RSS reader I also recommend Vienna RSS reader.