Normally I agree Joel's articles, but having dealt with the new garbage that Microsoft calls a standard, Office Open XML, I can tell you that none of this applies. Yet the Open XML spec is over 6000 pages long (compared to these binary specs which are a measly 100-300 pages each).
Open XML is not designed for performance... it's XML, and today's computers are fast enough. It IS [supposed to be] designed for interoperability (somehow they managed to get ECMA to put their stamp of approval on it), but in reality it feels like it's a half-assed attempt to wrap all of Office's legacy formats in XML. For example, to import you still need WMF importing, because a lot of the graphics (including all clip art) are WMF.
Open XML is not designed for performance... it's XML, and today's computers are fast enough. It IS [supposed to be] designed for interoperability (somehow they managed to get ECMA to put their stamp of approval on it), but in reality it feels like it's a half-assed attempt to wrap all of Office's legacy formats in XML. For example, to import you still need WMF importing, because a lot of the graphics (including all clip art) are WMF.