iOS 8 doesn't have a Camera Roll any more. The pictures that were in that album, and all the other ones (from former PhotoStream, Imported Photos, ...) can now be found in the Photos app in the Photos tab, under Years/Collections/Moments. Photos/images/screenshots you add, will be visible there, organized by date (and location, if available).
The Albums tab is now different. It shows Recently Added. If my information is right, the pictures there are only shown for a certain amount of time (30 days). Then there's Recently Deleted. When you remove images, they will still be available for 30 days afterwards. Favorites will show all your favorited pictures, and Hidden is for images you hide in Photos - Photos.
So if you want to see all your pictures, go to the Photos tab, they should be there.