Fortunately I got this as a lightning deal, so it wasn't that expensive.  I purchased it in October, but didn't start using it on my Samsung Galaxy S3 until January.  It was fine, until it wasn't.  It chose to die today.  Just a little more than four months after I started using it.  I checked my phone this morning and it told me that the SD card had been unmounted.  I did not think much of it.  But when I rebooted my phone and was still unable to find the card, I began to be concerned.  When I got home from work, I put a different card in, and it worked fine.  I tried to check the card on my computer, and it couldn't be seen.  So the problem is definitely a card.  Unfortunately, I lost most of the pictures I've taken since getting this phone.  I know that I probably should have backed them up, but I really didn't expect the card to fail so quickly.  Perhaps if I'd read all of the one start posts before buying, I would have.  Oh well, back to my 16GB Amazon Class 10 card until I can get a different one.I'm not even going to bother with a warranty claim.  I don't need another card that will fail after four months.