Many science fiction writers - including myself, Roger MacBride Allen, Gerald Brandt, Jeffrey A. Carver, Arthur C. Clarke, David Gerrold, Terence M. Green, James Gunn, Matthew Hughes, Donald Kingsbury, Eric Kotani, Paul Levinson, George R. R. Martin, Vonda McIntyre, Kit Reed, Jennifer Roberson, and Edo van Belkom - continue to use WordStar for DOS as our writing tool of choice.
Still, most of us have endured years of mindless criticism of our decision, usually from WordPerfect users, and especially from WordPerfect users who have never tried anything but that program. I've used WordStar, WordPerfect, Word, MultiMate, Sprint, XyWrite, and just about every other MS-DOS and Windows word-processing package, and WordStar is by far my favorite choice for creative composition at the keyboard.
That's the key point: aiding creative composition. To understand how WordStar does that better than other programs, let me start with a little history.
An old article from 1990 and updated in 1996, reprinted, but still a good read.