I recently acquire the Sigma 19mm for NEX and I've now written up a short review on my blog with some sample shots. My conclusion: "for $200 this lens is great value for a very good lens. If you already have the 16mm you might decide to give this lens a miss. If you don't, having used both, I would recommend the 19mm over the 16mm. Apart from the (for me) more comfortable size and better image quality, I also find the focal length a little more useful for a prime."