As a longtime Office power user, I find the iWork suite lacking. It's a nice set of programs and will be fine for the home/casual user who create files natively within those apps but anybody used to getting serious work done in Office will be quickly frustrated with the limitations of them. For example, most Excel spreadsheets with pivot tables will simply not open with Numbers.
I ended up getting Office365 which I highly recommend. For $99 a year, you get to install the full Office on up to five devices, be they Mac or Windows.