Harley, I've not yet used the 8-16mm on my NEX-5n, but have used it extensively on the NEX-5, and I'm particularly pleased with it. You are right that it is useful from 10mm up, where it has less (in fact, negligible) distortion, and few problems with corner sharpness. In fact, it is remarkably sharp across the frame. However, I'm impressed by it even at 8mm, where the distortion is not too bad (although often noticeable), and the sharpness is quite good as long as you don't have anything noticeable in the corners, particularly at f/8!
This may sound strange, but on my copy of the lens, at 8mm, the corners show marked astigmatism, giving smeared images, in the vicinity of f/8, but not so much at other apertures. At least one reviewer has commented adversely on the astigmatism of this lens, and it is certainly present, although it is not an issue in the upper half of the zoom range, and even at 8mm it is not a major problem up to about f/5.6 or above about f/11. In case you think I'm completely mad, take a look at the graph of "blur index" in this review:
http://www.slrgear.com/reviews/showproduct.php/product/1330/cat/all . They seem to have noticed something similar. Nettar
