One reason for the confusion relating to Camera Roll is probably that when you try to share a photo to Facebook or similar the album that the phone shows by default used to be Camera Roll and now is Recently Added (although Facebook still labels it as Camera Roll).
Given that this shows only the photos taken over the past 30 days, it’s no wonder people thought their photos had been deleted.
For now at least, if you want to share a photo on Facebook that is more than 30 days old you need to add that photo to an album, and then tap on Camera Roll and select the image from that album.
Creating albums isn’t a new feature of iOS 8 but given the above situation, you may wish to create albums for your images to make it easier to find them when using apps like Facebook.
View the photos, tap Select and pick the photos you wish to add to the album.
At this point we usually find it frustrating that we only see a square thumbnail of the shot because it is hard to see the detail and determine how good the photo is. We tend to flick through, opening images, noting which image it was as it closes, and then tapping Select and ticking that image.
When an image or images are selected tap Add To and select the Album you wish to add to, or scroll to the bottom and hit New Album to create a new album.
Now when you try and share the images on Facebook all you need to do is select the relevant album.
Read: How to share photos from iPhone or Mac to iPad