I used it a little bit back when I still wrote Python. It seemed a lot like HTML, but much terser, and whitespace-sensitive. ReST could do the same kind of stuff as HTML: build bullet lists, create tables, italic text, and so forth. However, since I had already learned HTML, learning another language that did the same thing felt like a waste of time. I fully believe that Restructured Text is a better markup language than HTML in some ways; however, I simply don't care because the differences are minor, and HTML is so much more powerful.
On the other hand, TeX was developed by Donald Knuth, a guy who spent his entire life doing research and writing papers about it. It has excellent math support, and is a true semantic language. I've written a few papers in TeX and been very happy with it.
Anyway, if RestructuredText were good at typesetting research papers, there would be no need for this project, would there?