$50/year per employee using the system seems like a great price point. Here in Arizona, the university system has transitioned to using GMail - at a great cost savings. Since Writely does a good job of importing Microsoft Word documents, transitioning most staff off of Microsoft Office seems possible for many organizations. Add in the benefit of shared calendars and GMail, and this seems like a slam dunk decision - at least it would be for me if I had employees in my business.
Often "less is more" when trying to maximize productivity. I often think that too many features in 'productivity' software actually slow people down when the core process involves thinking about a problem, finding solutions, and communicating with customers and co-workers in a simple and efficient way.