I've been able to open docx without apparent problems. We get docs from a range of MSOffice versions (97 - 2010, Win/Mac), with fair to poor cross-compatibility in terms of preserving formatting (or even being able to open). Libre does it just as well, maybe even better IME, especially with the newer MSO versions.
Haven't tried spreadsheets, nor heard good things about the ppt thing in terms of compatability with MS originals.
EDITED: 21 Jan 2013 12:14 by DSMITHHFX