Failed after one month and the problem is epidemic on the sandisk forums , they slowly get corrupted then fail and report only 30-32mb size.The Lifetime warranty is nice, but these products are clearly defective , I'm in the process of RMA now, will update post on status updates.DO NOT TRUST YOUR DATA WITH THIS PRODUCT, KEEP A BACKUP OF EVERYTHING YOU PUT ON IT, I'M 100% serious, just look at the sandisk 'users' forum for 64gb cards.Here is my breakdown while it lastedSanDisk Ultra 64 GB microSDXC Class 10 UHS-1Write speed  was 8-10 Mb/s (usually 8, tested windows usb 3.0 reader, and android)Read speed 27 mb/sFAILED @ 1 1/2 monthsUpdate 2-13-14Received back replacement item in brand new condition readspeed is 40+mb/s write speed is still around 10-12mb/s - RMA turn around time was about 3 weeks, I will up rating if this one lasts longer then one month.Update 5-1-14RMA replacement is still going strong, upped the star rating by one point.