I've had the 100-400 for over a year and have taken over 10,000 photos with it. I love the lens, it is sharp, easy to use, very light and portable for its reach, and produces great images for me. I shoot exclusively hand held and use it mostly for bird photography. With IS I can get useable images down to about 1/100. My only regret is that it doesn't work with the 1.4 or 2 teleconverter.