A fair comparison is to the DJI 15mm or Olympus 12mm as mentioned earlier. In looking to add a wider angle shot the field of view is the important factor.
SLR Magic 8mm - FOV Horizontally 103.9 degrees, Vertically 73.5 degrees
Olympus 12mm - FOV Horizontally 71.6 degrees, Vertically 56.8 degrees
DJI 15mm – FOV Horizontally 60.0 degrees, Vertically 46.8 degrees
The SLR Magic 8mm has more than 30 degree more field of view when compared to the DJI 15mm. This is a whopping difference and a big plus for the lens. Of course with more in the view, if you were to compare the same object (say a house) in shots form the same position the wider shot would contain less pixels of the house because it has to fit more on the sensor. This isn't an issue because you wouldn't be using this lens and wanting to crop in on objects. Another thing to watch is when shooting video and moving forward quickly, the props from the drone can now get in shot (similar to how it does in a DJI Phantom). The remedy is simple and it's just a matter of making sure you raise the landing gear.
All in all, I'm happy with this lens and it will be used pretty much on a daily basis in combination with other lenses for an all round package. Great work SLR Magic.