I used it for an e-book giveaway. As long as you make sure that you follow the style guide the results are pretty good, but there are a few snags that came up which it didn't cover.
Some characters don't go through the conversion process e.g. I lost my en-dash character. Also, smart quotes and apostrophes appear OK on most formats but play havoc with .txt. If you don't want .txt it's not an issue, but if you do, make sure you've removed them all.
Overall though it's quick, fairly simple, and free. I don't know how good it would be for commercial publishing, so you'd need to ask someone else about royalties, copyright etc.