The new 28-300L is a push-pull design which some people hate and some love. It has the latest IS which is very nice. But it does not have a constant aperture over its zoom range, which is something I like to see. At 300mm it is f5.6, which is not that great. I would like to know at what mm iit goes from F4 to F5.6. It uses the standard 77mm filter thread (good thing). It seems a bit heavy for a walk-around lens, 3.7 lbs. That is half a pound heavier than the 70-200L F2.8 IS lens, and 3/4 pound heavier than the 100-400L IS.