Well it's a rental, but I've got it for the next week, and so far, this thing is awesome! I'll have it at the track this weekend for the ALMS race. The first impression it made on me is how heavy it is. There's something like 21 glass elements in it, so it's not suprising that it weighs a lot. It's gonna take some getting used to for panning, but it shouldn't be a problem. It's also different in that it uses a "push-pull" mechanism to adjust the focal length. I thought it'd be annoying, but it really isn't at all. I can't wait to get out to the track with it on thursday!