Apache OpenOffice is a free office-suite alternative to Microsoft Office or Apple's iWork Suite. With open-source development, features constantly change and improve, which makes OpenOffice in some ways more flexible than its paid counterparts. While bugs are bound to be an issue, this is an all-around powerful, accessible tool set for anyone who needs productivity software.
Near-complete tool set: Apache OpenOffice's biggest selling point is that it can almost completely replace Microsoft Office. OpenOffice can open all of its counterpart's file formats and runs a smaller module. While it may not have the same sleek, modern look as the most recent editions of Microsoft Office or iWork, OpenOffice can easily handle all the same types of documents and tasks.
Streamlined interface: Some open source tools can be intimidating to use, but OpenOffice has a straightforward and feature-loaded but accessible interface. For basic word processing, number crunching, or creating presentations, the apps in OpenOffice offer everything you need, front and center. For advanced users, there are dozens more tools behind the scenes.
Some functions can be clunky: OpenOffice doesn't have the massive development cycle and resources that a major release from Microsoft or Apple gets, so there are some rough edges. While OpenOffice works perfectly for basic functions, more advanced actions -- like formatting documents with images, managing massive files, or running multiple instances at once -- can make the software slower. These are small issues, but power users in a hurry might find them a problem.
Apache OpenOffice is a very good free, accessible alternative to expensive office software. It is loaded with tools; downloads and installs quickly; and handles all the basic functions you could need from an office suite.