Hi All,
Three things I have found that worked for me are below. These ideas are already posted here, but worth repeating because one or using all three together worked for me. Before you start the process, I would make sure that you close all running apps on the computer and iPhone so that the photo app can utilize the memory and processor.
---Different iPhone Cable - As previously stated, try a different iPhone cable. For instance, one I tried would cause the photo app to freeze at a certain point, but another would work fine. The brand of cable didn't matter for me. One of my non-Apple cables worked for me.
---Different computer - The older computer would freeze, but the new one worked with the working cable.
---Make sure your iPhone stays unlocked while the copy is in process.
Best of luck,
Don