I have been using Sony 1 Tb External Hard Drive for last 3 years, i have also bought 1 tb seagate comparing to seagate the write speed of sony external hard disk is very slow but the read speed is about same.
Sony external hardisk have less quality as compared to other big manufactures like seagate and western digital. sony also take long time like one month as a service time if your hard disk drive fails. I had a bad experience using sony external hard disk drive.