Migrating photographs from iPhotos to Photos on iPhone 4s after iOS8 update

After updating my iPhone 4s to iOS8.1.3 I got a message saying iPhoto is not supported and to migrate my photographs to Photos. I clicked the Migrate button but did not get a progress bar or a message to confirm the migration had taken place. However, I can see the same photos in both Apps.

Is it safe to delete the iPhotos App without losing my photographs?