I was forced to buy one of these recently,and so would recommend that all premium console owners buy one.
Basically my xbox hard drive developed a fault,and i was unable to use the console unless the hard drive was detached,so xbox support are sending me a replacement hard drive,but i lost all my save games,so while i wait i had to buy one of these,and i'm going to back up any important game saves on this in the future,as if it happens again with the hard drive,i'll lose all my careers AGAIN.
Do not hesitate,as i have many friends with xboxs' that have also developed faults