Amazon just got these back in stock and I am considering ordering one. Does anyone where actually use this lens? I know Ken Rockwell loves it but you never know when to trust what he says I heard its a really nice lens but I cant see a $200 lens being as good as some of the more expensive lenses out there. I want a faster lens but I am not sure if I should go for this or wait and save up for something better. What do you think?