I probably should have asked before purchasing, but oh well. I have the Canon EF 75-300mm III lens, at least 11 years old. Over the past few months I have become very unsatisfied with it. It doesnt seem to be very sharp, slow to focus (almost impossible in low to medium light), and creep is terrible. So, last night I ordered the EF 100-300mm USM AF from Adorama. Im assuming this lens will be an improvement, especially with the USM. What are others thoughts about the 100-300mm compared to the 75-300mm, is it worth the money? Anyone using the 100-300mm currently and if so are you satisfied with it?