I have a Sandisk 32gb Class 10 UHC1 in my S4. I found that trying to get the phone to format the card failed, and therefore made the card unreadable. I put the card in my laptop and did a complete format. Not a quick format. Complete format, FAT32 file system. The card works flawlessly. I feel like people's card problems are related more to finicky formatting rather than manufacturing.
As for losing all your photos when a memory card dies, that is 100% user failure. There is absolutely no excuse for losing all your photos, because all your photos should not be permanently living on a single memory card in your phone and nowhere else. Your photos should be getting stored elsewhere for a permanent home. Cloud storage such as Dropbox and Google are all completely automated, integrated, and free. And you have the capacity of whatever hard drive space you have at home too. The only photos you should permanently lose in the case of a dead card or lost phone are the few recently taken ones that haven't been stored elsewhere.
Galaxy S4 on the Sprint Almost "Now" Network
- Carbon KitKat (NAE)
- TWRP Recovery
- 16016 PRL for full high speed 3G while roaming!
- Google Everything. It runs my life. It's my bitch. Or I'm google's bitch. Maybe both.