LibreOffice is indeed a great open source office suite, but I found it to be too unstable on mac OS to be of any real use unfortunately.

This suite is the closest to overthrowing MSOffice. You can save Calc and Impress Files under word formats and they will pass over with precisely 0 problems. Excel to Libreoffice may be problematic. Also, Calc has no auto-calculate facility, but a basic hand-held calculator is much cheaper and easier to use than Excel.

When I insert big image files, LibreOffice become very slow, so I have to resize images before.

I deleted LibreOffice and went back to WPS Office 2014, an older version (9.1.0.4758) which was the last release before it went to a freemium product. Libre is slow as molasses, especially when starting cold. The developers could cut the execution time considerably by making the install more optional, such as only installing the writer and spreadsheet, instead of the whole suite...or making a stand-alone writer...but they've never had any interest in doing this. WPS Office, even with its three programs, is lightening fast and still the most compatible with Microsoft documents. Libre's recent face-lift is an improvement, but WPS Office still wins in speed, interface, and compatibility.

If you still have doubts about replacing the traditional Microsoft Office suite with this marvel, just keep in mind that it's number of "likes" triples those of the traditional Office. No more to say.

Do yourself a favor, forget about other suits like Microsoft Office, etc.

This comment is just a random thought: the Mac icon for LibreOffice is really ugly. Yes, it's the same icon as on Windows. But it just doesn't look right on the Mac. especially when you compare it with the icons for Apple's default apps, or even with other 3rd-party Mac apps. My biggest complaint would probably be that the icon is too big; it's noticeably larger than any other icon on my dock, and it doesn't help that 90% of the icon is just plain white. So yeah, it's a bit of an eyesore.

LibreOffice looks the exact same as OpenOffice.org, so don't expect some magical intensification of your daily productivity when you switch. The Document Foundation has only added a few small features, most of which work in the background, to the original OpenOffice.org suite (so far).

This piece of software is essentially a big middle-finger to Oracle, and though it further complicates the market of MS Office alternatives, it's quite nice and my new default Office app!

well... actually it is not a fork but a real OpenOffice.org... it seams that developers of open office decided to create LibreOffice after Oracle bought Sun Microsystems... details here: http://www.documentfoundation.org/faq/