The improvements in V1.3.1 seem to be downgrades compared to v1.2.4 (which I have).
In V1.3.1, some pictures are zoomed in and you can't zoom out. They appear cropped in USBSharpPro but really isn't. In V1.2.4, some were also zoomed in but you can pinch to zoom out to see the rest of the picture.
Another thing wrong is that while V1.3.1 has a smooth transition to other pictures when swiping left or right, it gets stuck sometimes. When I was swiping left or right quickly, the picture would still appear when it was suppose to change into the next one. In v1.2.4, the transition wasn't smooth but worked compared to the newest update.
What USBSharpPro needs is a fix to its current problems and new features such as a gif player. That would really make USBSharpPro shine. But as its now $2.99 for the pro version, it doesn't seem worth the money.
I guess I'll still be at v1.2.4 till there's a good update.