Rented this lens just this past weekend and I'm totally in love with it. I only wish I had purchased this lens before I got my 70-200m lens.
This lens was so much fun to use and my outputs were just amazing. Great in low light at f/4.0. Great color. Like I said it's a bit heavy with my 40D. Can't wait to rent it again. At the same time saving my pennies to buy this baby. Maybe my wife will buy it for me for Xmas.