What Tom and Peter have said is good advice, but I'll offer a different perspective. First, you need to evaluate exactly what you need to do with your documents. If you will be continually interacting with colleagues who use Office, then you're going to find yourself continually changing file formats if you use iWorks.
I worked with MS Office for years, but only because of the aforementioned reasons. Most of us recall when iWorks was not quite so dumbed-down (a move to make the apps more iOS compatible), and back then iWorks ran a closer race with Office. However, I've recently retired and don't have nearly the dependency on Office files so I moved 100% to iWorks. The reason for me is pure simplicity and elegance...iWorks apps are easy to use, not nearly as complex, are exportable to Office format when the occasional need arises, and I simply like iWorks better. It's "Apple".
I don't dislike Microsoft at all...I use OneDrive for cloud storage and it's filled with hundreds of iWorks documents. If I open any of these on my Mac the corresponding iWorks app is launched...the same happens on my iPhone or iPad. (If Apple would ever "get it" regarding what users need from the cloud, I'd move to iCloud, but it's probably not going to happen in my lifetime.
So, even though it's great advice to really think hard before you move to give up Office...don't forgot to think equally as hard about the benefits of moving to iWorks, even in a world where Office still prevails. If you find you really need Office...use it. If not, iWorks just might be a lighter and less complex solution.