well, the difference is obvious.i hated it, turned it off.
Its ok when you have already very high frames, but it sucks big time when you need it the most, in low FPS situations. Also, the decrease in image quality gets more and more obvious the lower the frames are.
Its pretty bad overall, compared to native. and it has more downsides, like latency, no VSYNC, frametimes are all over the place.