As mentioned earlier in the review, currently there are not that many choices out there for native Sony NEX mount UWA lenses. If you're shooting m43 cameras, you are lucky - there is a ton of opptions available, but Sony users are stuck with either a rather mediocre Sony E 16/2.8 lens or super-expensive Sony Zeiss 24/1.8 lens. A possible solution is to use an Alpha mount UWA lens like Minolta/Sony AF 20/2.8 with an E-LA1/E-LA2 adapter. Or opt for a fish-eye like Samyang 8mm f/3.5 and use a PTLens distortion correction to fix the fish-eye effect. If you don't mind shooting in a manual mode, then a wide selection of rangefinder lenses like Voigtlander Ultra Wide Heliar 12/5.6 and Voigtlander Wide Heliar 15/4.5, or any of the UWA Nikkor Ai/Ai-S lenses should also be considered.
As a new entrant into the NEX market segment, Sigma is certainly doing quite well. Sigma 19/2.8 EX DN is the company's second solid offering (the first one was 30/2.8 EX DN) for this system. While the lens might not offer any bells and whistles and does not carry the premium brand name recognition like Zeiss does, Sigma 19/2.8 does a lot of things right - price, resolution, color are all things that, while not absolutely remarkable, are done right in this lens. As one would expect, the lens is not without its weaknesses - some CA, some distortion, some flare and some vignetting, but all of which can either be corrected for or minimized under right circumstances. Bottom line is that this is a fairly good lens in the rather limited selection UWA market for NEX.