If it Hangs, Do This:
This app seems to work well for contacts, notes and a few photos, but like others, when I tried to move a lot of photos (8,500) from an old iPhone 4S to my 8 Plus, the app would stall, usually after it had moved 1,500 - 2,000. I tried leaving it for a couple hours, hoping it was just buffering and would catch up, but after two hours, it was still on the same image.
After a little trial and error, I discovered that I could move them in batches. Be warned— it’s not difficult but it IS time consuming! Fortunately, the app is thorough, and it moves the photos from the old phone in order, starting at the top (oldest photos.) Here is the procedure that worked for me:
1) Move the first batch according to the directions. (I unchecked everything but photos, from the four options the app gives you, because that’s all I needed to move.)
2) When it hangs, close out of the app on both phones, returning to your home screen. At this point, it’s best to give the new phone an hour or so, connected to WiFi, because it is still uploading photos.
3) Now for the time-consuming part— deleting the images from the old phone that have been duplicated onto the new phone.
Open the photo file on both phones and on the old phone, scroll to the very top— the first photos. On the new phone scroll to where the moved photos begin (after your most recent photos).
With the phones side-by-side, SELECT the images on the old phone (add a check mark) that you see are on the new phone.
I check about 80 images at a time, and then delete by touching the trash can.
It’s much faster to compare entire rows of four, rather than individual images, so if you need to, delete 1-3 images until the rows match up. If there’s an image missing (it isn’t on the new phone), just skip it for now because it’s still loading (the reason I give it an hour or so.)
When you get to the last image on your new phone, you’re done. The images that have been copied onto your new phone have been deleted from the old phone, leaving only the images that still need to be copied. So basically, you’ve moved the first batch. Time to start over.
4) Make sure you're still connected to WiFi, and open the app on both phones. Go through the menu again. If it finds your phones again, great— proceed to move some more images. When it hangs, repeat steps 2-4. If it DOESN’T recognize your phones and show them, you can try resetting the WiFi according to their directions. If that doesn’t work, go to step 5.
5) Reset the WiFi, as above. Remove the app from both phones. (Press the app icon until it jiggles, tap the x.) Do a reset on both phones. (Hold the ON button until the slide appears, power off. Wait 30 seconds. Hold the ON button until the Apple logo appears, wait for your home screen.) Download the app again to both phones. Start the apps and proceed normally— it should find your phones now.
Like I said, it’s time consuming, but I was able to successfully move 8,500 images this way— 1,500-2,000 at a time. I hope at some point they’ll fix the glitch so you can move a large number at once.