Controlled blurs can take a flat image and add interest to the subject. Photographers have used depth of field to create great photographs for many years, and over the last couple years, Adobe has made it possible to apply the tilt-shift look to any photograph.
The process of using the Blur Gallery is not just a slider for blur, but also the control of what is fully blurred, not blurred and the distance of transition between. This level of control is really valuable and powerful when working with your photographs.
LINK: Adobe > Walkthrough of Tilt, Field and Iris blurs