Solid State Drives in Keeping Files

I know that Solid State Drives have faster read and write access times than regular hard disk drives. However, I also know that flash memory found in SSDs cannot retain files longer than the drives that we are using today cause I experienced it myself in some of my Flash Disks. What is your experience in keeping files using solid state drives? How many months/years can it sustain the files and leave it uncorrupted if it is not connected to the computer?
