As others have said, a major step backwards. The UI was "refreshed" to a crappy non-standard Mac app standard. A few examples: it doesn't use the system toolbar API, it places toolbar icons (without option of text under icon) in window title bar, and it's missing a File menu. I have a feeling whomever "developed" v4 is not originally a Mac developer, but rather one of the those "I use a Mac just because I wanted to start iOS development" people. To top it off, it looks like a crappy copy of ReadKit now. I like ReadKit, but NetNewsWire v1-3 catered to a different audience; the original Mac "Pro" user. Too bad Black Pixel abandoned this audience.