Originally Posted by Toxaris
Please advise them not to. Adding a font does not always work as expected and will add weight to the book. In this case it doesn't seem to have significant advantage. Try to keep the usage of non-default fonts just for headers or special cases.
Simon & Shuster are using embedded fonts for their Star Trek ePub and I do think they look nice that way.
There is nothing wrong with embedding fonts. One I quite like is Charis SIL. It's a serif font and a serif font is better for reading a book then sans-serif (IMHO and most people on MR who took the poll).