For an individual, probably not. I've been an OpenOffice and LibreOffice use for my personal use and contracting business since 2004. I've had no need for "real" Microsoft Office in that time. I also don't deal in macro-encrusted documents or with more esoteric features.

For an org where individual users aren't technical I'd never try to get by w/o Microsoft Office. The assumption by all large orgs. that you're going to use Microsoft Office is pervasive. Even if the Free Office suites work fine tech support is always going to be mired down in compatibility issues, both real and perceived.