Well uh ... it's just software I found recommended in some huge list of open source programs. I've never used it. But someone was asking for writing programs, so I figured I'd recommend it and use them as a test subject.
It seems like it might be useful, though. It has an outliner, distraction-free mode, simple and fiction modes, a frequency analyzer for seeing what words you use too often ... all sorts of features. I've no clue how well it compares to Scrivener, but at least it's free. You can check it out here