I cannot rate an app that doesn't do what it is intended. Nor will I purchase an app without proving that it works as intended. So I ran cardrescue on a 16GB sd card. To be fair I only tried it twice on the same card. Both times the progress bar goes to 50% ca. and then it appears to stall. Waiting all day didn't give any results. So no go for me. It does say in the app description..."it will try to..." and that's not a promise of success. Cards vary and have all kinds of manufacturer quirks that can be extremely complicated for recovery. Memory card standards vary and use different hardware indexing then a hard drive which is more straight forward when it comes to recovery. I have read reports that it is impossible to completely destroy data on some cards. Even a "secure Delete" won't go through all the levels and indexing of the hardware to completely and securely delete. Just re-appropriate the space.