It is an interesting new lens with fisheye effect on FF between 9-14mm. At 15mm, it does not have any more fisheye effect. This will allow people who are interested in UWA to try out the fisheye effect without investing in a separate lens. Personally, for a lens at this UWA angle, large aperture is not a requirement as I will usually stop down to f/8 or above for landscapes. Of course, flexibility is good, but I would rather not pay for something I don't need.