A university professor explains what his finding where when he tracked how much he needed Flash during his day, and how not having it would impact his daily productivity at work. Check out the full article by following a link to his blog below.
Personally, I was rather surprised at the results. The darker green slice (above) means that Flash Player was required to experience all the content of the site. A full 69% of the all sites I visited yesterday required Flash Player to fully experience the site. Some would have been incredibly difficult to navigate without Flash Player (for example, Total Training). Others have alternatives to using Flash Player (such as Lynda.com), but I would have had to change my established player preferences at that site (which I chose not to do).