I have tested the SJ4000 in Australia. My Conclusion: The operation is very intuitive and easy. Picture quality is adequate, people who like to have high-quality photos is, however, not recommended purchase. The SJ4000 comes with different lighting conditions cope not good. In sunlight, the images are overexposed and weak in color. In the dark you can not see anything. I expected it and it used exclusively for films. These are quite good in spite of changing lighting conditions. We had a direct comparison with images of GoPro. The photos of the GoPro are all better than the SJ4000.
However, for small money and the gimmick it is nevertheless recommended.
