I have the same problem. I restored from an iCloud backup after erasing all content. Everything's back to normal. Except for the Camera Roll. It remains empty. It only downloaded the last 15 pictures from my Photostream. For a few minutes my photos app showed "Downloading 0 from 1327 photos". After a while that was gone as well.
I'm sure my restored iCloud backup should still contain these pictures as it states that the backup size is 4,5 GB. My camera roll was about 3,2 GB so that makes sense.
Anyone got an idea on how to sort of restart the process that will download the photos from iCloud? I'm trying to figure this out for more than a week now and it's really starting to **** me off. Two and a half years of pictures are gone!