I wanted an external hard disk to backup my photos and this fitted the bill. It is small but transfer time is fast. It took about 60 minutes to backup 41GB of data which isn't bad. The backup software has the option to only back up files that have changed but this doesn't seem particulary efficient since it took 30 minutes to determine that only one file needed updating.
One word of caution, you need 2 USB ports, one for the power supply and one for the data link.