The problem with OOXML is that Microsoft shoehorned the format in Office 2007
as Traditional OOXML, meaning that it had a reliance on Microsoft's programs
and was a mess. Microsoft wasn't even complete with the specification and
doesn't follow the ISO standards, which is known as Strict OOXML.
According to
http://blogs.office.com/2012/08/13/new-file-format-options-in-the-new-office/
only Office 2013 is able to fully open, edit, and save Strict OOXML files.
Office 2010 was able to open them, but it saved in the Transitional format.
This is a big issue as only the most recent versions of Office actually
support the proper ISO specification of a format released 5+ years prior.
If OOXML was Strict from the start, then we wouldn't have these issues now
regarding document preservation between various versions of OOXML. That's
where ODF comes in as being the best option by having clear and well
documented specifications from the start.
