This lens sounds incredible. I have been waiting for something around the 500mm with good IS, and f5.6, this definitely covers those specs, but the price just wrecks it for me. I didn't expect it to be cheaper than that and for what it offers and compared to recent big white releases it will be worth the investment.

But as an amateur that's too much for me, I think I will have to live in hope that Sigma release something special around the 500mm mark with good OS.