Conclusion: It is worth every penny. Yes, certainly, at the edges can be seen in wide-angle, a blur at 100% Photoshop / LR. But, dear critics: This is normal. Normal for the price, normally for 16 millimeters. Who should be a little familiar with the laws of optics to know the rest of it may indeed read. And all those who once made a print, after they had frightened at said full view, will find that this Pixelpeeper view also has much academic. When noise, sometimes along the way, the behaves similarly.
But more to the beat: The sharpness is excellent, the color fastness and very good resolution, you can even without stabilizer with long periods out of hand shooting (as opposed to 24-105 4.0 for example) and the distortion is kept within limits. My Super 10-24 mm lens APS at the Nikom distorted more, although expensive (yes, apples and pears, I know). Lightroom corrected quickly and reliably, all good.
Solely this a millimeter, I would have liked. May sound stupid, but I know how something looks, and that makes more than you think. On the other hand, that's a pretty expensive millimeter and who does not necessarily need it, these optics can buy without risk.
A comment yet for Panned here: I wrote this review because I just take pictures with full frame and the statement that the 17-40 to not be able to simply can not agree. At least not to my clippers. There are certainly camera-lens combinations that do not fit, as well as quality variations of which I can sing a long, sad song. But you should not paint the town red, if you did not have at least one identical model to the camera.
