After a month in operation, I must say - everything is relative! I am very pleased with the lens. The touch zoom is to use very well in my opinion. So you can travel long distances in a short time push. The image performance is very good for my circumstances. When it comes to auto focus, I could not notice any problems. Sitting where I want him.
I can assure all doubting interested only guess, buy! Sure, here it is not a bargain, but processing, performance, features and stability justify the price in some way.
In conclusion: I am pure amateur photographer. Until I lifted the full potential of this lens, two other successor will certainly be released. ; O)