LyX produces high quality, professional output -- using LaTeX, an industrial strength typesetting engine, in the background; LyX is far more than a front-end to LaTeX, however. No knowledge of LaTeX is necessary to use LyX, although it will give a user more power.
LyX is stable and fully featured. It has been used for documents as large as a thesis, or as small as a business letter. Despite its simple GUI interface (available in many languages), it supports tables, figures, and hyperlinked cross-references, and has a best-of-breed math editor.
