Wanting to experiment with creating my own e-books was what tipped me over into trying Scrivener as writing software. At that time, I wasn't entirely convinced that it would be the sliced bread of composition tools, but the fact that it included integrated utilities for outputting the content in the three standard e-book formats (epub, mobi, pdf), as well as in standard manuscript format, made it worth the try.

I haven't used it for an entire book-length work yet, or for a non-fiction work, but I've done a couple of short stories just to get the hang of things. The Musketeer story will be interesting, given that I want to add a bunch of back matter. I also think they should come up with an "anthology or collection" template that will automatically take care of handling the previous publication and/or multi-author aspects of that sort of work. (I haven't gotten around to suggesting it, and for all I know, something of the sort may be in the works.)