I installed FlickStackr on my iPad 3 iOS 9 without any problems. It runs quickly and is much faster to use than the official app. Navigation takes a little getting used to, but all the info like tags and exif are there once you learn where they are. Most importantly for me is that it returns the use of group discussions. That part could have been better organized but its good enough. Oddly, it seems like the photo renderings are displayed better in this app than in the official one. Note: 4 stars for me is pretty high. There are very few perfect apps out there.