The cameras on the Samsung Galaxy S6 have been very well received by users and reviewers alike, they are considered some of the best cameras ever used in a smartphone. The 16-megapixel sensor with OIS in the main camera produces crisp photos with lots of details and a good color reproduction whether the sensor is the Sony IMX240 or the Samsung ISOCELL one as recent reports have mentioned that the company is using two different kind of sensors on this model. On the front of the device, the 5-megapixel sensor with the same f/1.9 aperture as the main one and a wide-angle lens lets you capture more objects on the photo with the same good color reproduction and not a bad amount of digital noise. Now, let's face it, production problems are common within mobile devices and while we expect that the device we buy is perfect, there's a chance that we will find some kind of issue with it that we didn't notice when we first bought it.
Regarding the cameras, there are almost none know issues, although a problem with the LED flash of the main camera which doesn't turn off entirely has been reported. There is a new and more serious issue that some users are reporting on Reddit, it involves the front-facing camera and some blue or purplish dots that are present in every photo they take being more noticeable in low light conditions. The original poster mentions that the camera was fine for a few weeks and then the dots started appearing, and while it is possible that the conditions of the photos taken in that period of time aren't appropriate for the dots to show, it is not known if the sensor is affected by software or hardware. It is supposed to be an issue known to Samsung and apparently it seems to be hardware related because some users have been able to exchange their defective units for a new one, while others are relying on some retailers policies to exchange their devices against any defect for a certain period of time. Users at XDA forums are saying that the problem is corrected by changing the resolution to 3.8 megapixels, but this is not acceptable as you won't be able to use the full potential of the camera. There are no reports of the issue on the Galaxy S6 Edge yet.