I second JoeyR's opinion,
I have all office suites mentioned here, iWorks 09, MS Office for Mac 2008, NeoOffice and OpenOffice.
OpenOffice is complete, stable, and FREE... Is compatible with way more than iWorks and MS Office are (like, WordPerfect docs, anyone?), and is free...
It doesn't look as polished as iWorks or MS Office, but hey, it works better than MS Office, which crashes
very often if you have a heavy document with tons of multimedia like various graphs, tables, pictures, etc.
Did I mention it's complete, stable, and free?
😉