Bests & Worsts Reviews from Amazon

I have a couple Canvio drives in this exact size. one failed after several years of service. These new drives are horrible. At first I thought I just got a bad one (It happens) so I sent for a replacement. The new one is just as bad as the first. I get about 20 gigs transfered into it and the throughput drops off . I am not sure if it is due to heat or what, but it never increased in speed even after letting sit for an hour. (both drives)