If that is your only argument - Office2007 isn't compatible with Office2003/2000 either. So not a very good one.
The reason why LibreOffice sometimes "messes up" your layout is that it uses the "document structure" workflow instead of the "visual" workflow as seen with Word. Once you find out "Wait, I don't have to care about how this looks until I've finished with the report, and then I just change a few parameters", it's amazing how much Writer throws itself to be out of your way as much as possible.
With word I have to constantly mind what format I need to use. "Wait, should I use 12pt or 16pt text here? And was it Verdana or Times New Roman?" In LO - no need for that. "That's a headline, that one is a paragraph, that one is a bullet list, and there we have a quote." Mark text accordingly, insert emphasis where needed, done, no need to bother about looks at all, and it's easy as pie to, for instance, a table of contents. That's why I find LO superior.
Oh and now you might say "But word has that too!" - yes, and LO has the visual styles too. But in LO everything is designed through the document structure paradigm. In Word it's just a half-assed mess.
Finally, yes, LO Writer is quite a bit limited when designing, say, a pamphlet - but why on earth would you use a word processor to make a pamphlet? Get indesign or Scribus for that!