Ranked in these QuestionsQuestion Ranking
Pro Free and open source
Licensed under Apache License.
Pro Comprehensive suite of applications
Apache OpenOffice includes applications for word-processing, spreadsheets, presentations, and database management.
OpenOffice is available on Windows, Mac OS, and *nix systems.
Pro No CopyLeft
Unlike LibreOffice, its Grandfather OpenOffice is real open software for anyome.
OpenOffice is available in 170+ languages.
Pro Full compatibility with Microsoft
Fully compatible with Microsoft formats - from the oldest to the latest.
It has quickstart on Linux, a feature that makes opening a file blazing fast.
Con No copyleft
It's good for developers but bad for openoffice for example: libreoffice relicensed it under GPL now libreoffice can integrate all changes made to openoffice but openoffice is unable to integrate improvements from libreoffice.
Con Dead project
The project looks dead. They can't close even serious security vulnerabilities. You might want to use Libreoffice instead.
Con Documentation is lacking
OpenOffice documentation is incomplete and language is highly technical.