I've tried a couple of word processors out there, and nothing can really beat Word for the sheer number of features, bells and whistles that's rolled into it. But for practical usage, I prefer Google Docs. While Word is great for a number of different things, Google Docs is perfect for my writing. I can write at any computer I'm at as long as it has an Internet Connection, because the document is stored online. I can also organize my documents into folders, so I know where everything is, and exclude non-essential documents from my list.
Open office is brilliant for anyone that needs a full featured word processor without the expense. If you are looking for something that's free to save money, Open Office may be where you want to go. If you are looking for Mobility, I would definitely recommend Google Docs.