What-you-see-is-what-you-get: essential for advertising layout,
but a useless time-waster for a phone book.  WYSIWYG is the
opposite of SGML, in that in SGML you know what something
is (say, a chapter heading) but you don't know what it looks
like; in WYSIWYG you know what it looks like but you don't
know what it is.  The obvious benefit of WYSIWYG is that the
author is aware at all times of the final appearance of the
document; the liability is that the vendor gets to choose the
internal representation of the document, and may not tell you
what it is.

The best trade-off would be a WYSIWYG system with a well-documented,
usable markup language.  There is a system called "GRIF" - see
GN11.  The "doc" program in Interviews is a freeware UNIX WYSIWYG
wordprocessor.

We should caution that few of the self-proclaimed WYSIWYG systems
actually show the exact same thing on screen as you get on a printer:
What You See Is Sort Of Like What You Get.  When 300 dpi, 17 inch
terminals are common true WYSIWYG will be practical.

Being aware of the final appearance of a document is not universally
accepted as a "good thing", Robertson Davies has suggested that the
WYSIWYG approach to writing contributes to "blather" (and he should
know as a past master ;-), while others have argued that the final
appearance can't always be known.  WYSIWYG processors tend to
encourage an approach that makes re-use and re-packaging of
documents for alternate methods of presentation (eg: on-line
and paper documentation) difficult.  Efficiency studies have shown,
for at least certain types of documentation, that documents are
written faster with text processors than WYSIWYGS.