Wow so it is.....when I first tried it (post iOS 8) it wouldn't open Pages and Numbers docs....it does now.
EDIT. Put a hold on the above. I had some Pages and Numbers files in my Readdle Documents folder, and they opened, which they didn't before. So I added a new folder of PDF, Numbers and Pages docs to my Readdle Documents folder (using my Mac). The new folder shows up on the phone, but only the PDFs appear to be present??