The dude who wrote it seems like a nice guy who was scratching his own itch. Plus it supports Markdown! As you know, you should not be editing fiction in things that allow you to fuss with format, because then you will fuss with format.
Free to use, though you can buy a subscription if you want access to beta features. I am a satisfied customer.
Bonus music: Kerry Muzzey's "The Night Sky", with dance. This piece was inspired by NASA audio renderings of radio waves emitted by the earth. The music in turn inspired the dance. Just awesome.