I would say it can wait. The "bounce" behavior is pretty well understood on the platform. The other way to do it, if you feel that the order of the pictures represents some kind of progression, is to disable the "Left" button on the first picture and the "Right" button on the last picture.
A few other things I have noticed:
- The app doesn't tell me how many pictures there are and/or which picture I am on. That would help in knowing how far into the pictures you are, and give me a way to easily find a picture again.
- The app always starts at that first picture. It would be nice if it restarted where I left it. If I wanted to show a particular picture to someone, I've got to start the app and then swipe my way through.
- If you start swiping very quickly to try to motor through the pictures, it looks like the phone can't keep up and you end up with a black background for a bit.
- The "Random" has some kind of a bug that I've only been able to produce once where, when pressing it rapidly, I got the spinner to come up and never go away.
- "Random" generally results in the spinner getting shown, and then the screen simply displaying the new image. However, if the image is an image to the immediate left or right of the current image it does a swipe style animation to display it. It should probably be consistent and just pop the image on screen.
- A way to get to the beginning or the end might also be useful. Perhaps a double tap on the screen can alternate bouncing you between the first and last picture. You could use the double tap to bounce between the first and last picture for now, and in the future change use it to display a tiled "Camera Roll" style view.