BEWARE: Samsung Galaxy S6 Issues with this Charger [UPDATED]
While I am sure that the charger works well with other models, it has a few major problems with the Galaxy S6. Specifically, every time the S6 screen turns off to prevent burn-in on the OLED screen, the charger goes from blue (charging) to green (ready). The phone subsequently beeps twice, and the lock screen turns back on. The phone charges until the screen turns off again, then the cycle repeats. As you can well imagine, this is very problematic and irritating when you have the phone charger close to your bed at night - and let's tell the truth about it, don't we all?
The second problem, at least with the S6, has been mentioned in other posts. Heat. While charging on this charger, the back of the phone gets really hot. Not good for battery life, or electronics in general. I do not know that this is the fault of the charger, and may be a defect in the wireless charging design in the S6. Nevertheless, the issue exists with the S6 and this particular charger.
UPDATE: After receiving a reply from NeWisdom informing me that this was probably due to an underpowered adapter plug (one was not included with my charger when delivered, so I had been using one from a prior Galaxy phone), I swapped out the adapter for the one which came with the S6. The problem vanished instantly. According to the NeWisdom information I received, the wireless coils require more than the 1.5A provided by many adapters out there. Upon closer inspection, the S6 plug actually identifies it as an "Adaptive Fast Charging" device with an output of 1.67A at 9V, or 2.0A at 5V. Looking at my older adapter, it shows lower maximum output than even the 1.67A. One interesting note: the older adapter worked (and still works) fine when charging the phone plugged into the mini-USB port. But the wireless coils require the higher amperage.
NeWisdom also informed me that the temperature was not a problem, and that they have included a "safety temp control system" in the charger. As I have read other reviews of the Samsung branded wireless charger in which heat is mentioned, this appears to perhaps just be a side-effect of wireless charging in general.
With these two issues being addressed, I am changing my rating to 5-stars. This is a great, sleek unit and - once you use an adapter with sufficient power - it really works great! Special thanks to NeWisdom for pointing me in the right direction. Perhaps in the future they might include these instructions on the Amazon page, and/or begin including an adapter with sufficient amperage output with the unit.