The reason for IS is mainly for video. I want 1 lens as an all around lens and if I want to use this for video, I either need a tripod or another lens. That is not cool. Plus, a big use of this lens will be event photography and anyone shooting a wedding has taken pictures of the church, flowers, scenery, and other items where the shutter could be slowed down and ISO lowered. Not to mention in a wedding, people hardly move and it would be great to get away with 1/60 or slower shutter in my nervous hands. I'm shooting at ISO 1600-3200 alot in these ceremonies and every little bit helps.