I already switched from MS Office to OpenOffice for some time. But most of my friends and colleagues still use MS Office. At my workplace, most of the people are using MS Office. Some of them use MS Office 2007. I introduced OpenOffice to friends, but switching from one environment to another needs some time for adaption. So, normally they reject.
Why I want to use OpenOffice? Firstly, it is free. You can get it without paying any money, and do not have any license issue Secondly, it is open source. If you are developer, you can study and contribute. Thirdly, it is cross-platform. If you are not working with Windows, but Linux or FreeBSD, then how do you use MS Office? May be you will say that, “Why Linux? Why FreeBSD? We have Windows already.” Very good, you are very loyal, then go ahead. For me, learning more than one skill is always better. Fourthly, OpenOffice can satisfy my works: documents, spreadsheets, and presentations.
Now, I prefer using OpenOffice Writer. The Styles and Formatting feature is very useful. Though MS Word (2003, which I am using) has the feature also, setting the styles and formatting in OO Writer is easier.