It must be noted that when playing a classic game on an emulator, such as Callus or Nesticle, the quick save feature can be used to pretty much walk your way through even the most difficult of games.
Don't like the stats that you roll for yourself in that RPG? Press the quick save button before you roll, then you can press the quick load button if you get bad stats.
This feature has allowed me to do the impossible which is to finish Final Fantasy for the Nintendo using 4 White Mages (healers, for the uninformed). The quick save is also invaluable when in the dungeon in Wizardry (the way the game generates random numbers helps). Properly used the quick save will allow you to quickly become a Ninja or Lord, not to mention getting all of the rare equipment.