There are probably two camps of people out there when it comes to the Sigma 45mm f/2.8 DG DN Contemporary. One camp is surely asking what the fuzz is all about - after all it's a comparatively slow speed and expensive lens - whereas the other camp is rather enthusiastic about it because the lens combines high product quality in a low-profile package - perfectly aligned to street photography for instance. In terms of optical performance, the results are pretty impressive. The center quality is very sharp at f/2.8 and the outer image field is pretty good, too. Stopped down to medium aperture settings, the center reaches superb levels and the border/corners improve to very good quality. Lateral CAs are quite negligible. However, the native vignetting, as well as image distortion, are relatively high for such a lens but then Sony's image auto-correction will take care of this. The technical quality of the bokeh is decent albeit not perfect.

The mechanical quality of the lens is nothing short of outstanding and it puts much higher priced offerings to shame. The all-metal construction looks and feels great. And how often do we see a metal lens hood - and this one isn't just a smooth barrel but a fluted one. The damped(!) focus ring, as well as the addition of an aperture ring,  is also something special. If you are nit-picky you may criticize the partial weather-sealing. The AF is fast and silent.

The biggest flaw of the lens doesn't relate to its characteristic but to its name - it is just no "Contemporary" lens. It is ARTier than some designated ART lenses in Sigma's lineup for sure (BTW, ART is not about speed only - e.g. the Sigma 30mm f/2.8 DN ART is/was just as fast). So regarding the "love it" or "hate it" group question, yours truly is certainly in the first group - thus highly recommended! Your mileage may vary though.