Been doing a bit of research on this lens (yes I did search) and at first all the views were positive and I was thinking of going in and buying the lens then I ran across a heap of less positive reviews and that put me off it a bit - so I thought I'd say what I'm looking at using it for and seeing what people here that have the lens or have used it think. Yes I'm tempted to go up to the Canon, but that will wipe me out financially and I am about to go for a trip to the daintree rain forest. I'd like a good lens for that, but I also need some spending money lol. Mostly I will be using the lens for nature photography, but I would also want to use the lens for motorsport from time to time. Now I know the lens gets a bit soft at f2.8 - but I don't really think I'd shoot at f2.8 on it very often, that would be extreamly thin DOF I imagine on a telephoto? I'd like to take it for a spin but there is no lens rentals here. I have used a few Sigma lenses in my time, nothing that chunky but they have always seemed good lenses for me. I quite like that it sounds like you can make manual adjustments to the auto focus, that sounds really useful to me. Cheers in advance for your advice.