An interesting comment from document interop specialist Dr Peter Sefton, who knows his stuff:
As I've covered here many times ODF interoperability between applications is basically non-existent except between Microsoft Office and OpenOffice.org and its derivatives where some things work quite well. Bottom line is, ODF doesn't have any formal notion of what's conformant - it's up to application developers to implement the bits they feel like implementing.
From various other items on the web, I would say that you would be able to say exactly the same sentence but substitute OOXML for ODF.
The problem is that the bottom line for document interoperability is not the format, but the feature match of the applications. The only way ever to get reliable, bottom-line interchange (enough fidelity that no semantics are lost, with graceful degradation) is by restricting feature use.
An old trick we used to use with text processing in the pre-XML days was to deliberately save the document in some known-to-be-horrible format, then re-open, check, then save again in the high quality format. This helps with feature matching.
In modern times, you might consider first saving the document as HTML (or RTF! or even structured PDF!) and sending that *as well as* your ODF or OOXML version, if it is mission critical to have maximum reach.
The tide is certainly rising, though but unless we legislate (I am not serious here) for a global new-feature freeze on all office applications, the feature-match issue will never go away. It cannot.
Far from being signs of failure, the horrible dialog boxes that tell us, when we save, "Some features may be lost" are the way it should be.
Maybe mandating any base-line format, unless it is a horrible kitchen sink format which will have extreme coverage problems, necessarily involves saying "We are happy with some kinds of information loss."