When I save a Writer (5) document to Microsoft Word (2010) the format gets really messed up.
So what? It is a questions-and-answers site about LibreOffice.
What is exactly the question? Compatibility between formats is a very complex thing and the way you use Writer is a very important factor. Styling vs. manual formatting may make a big difference.
If you expect any help, edit your question to explain and, as @gabix says, this is a LO site. We can help about Writer, not about Word (at least for me, I have no Word on my Linux box).