TweakTown posted a review on the Western Digital My Book Mirror Edition External 2TB HDD:

The Western Digital My Book Mirror Edition is not unique in its features, but is one of the most widely available external hard drives to feature RAID. The included software suite is given a big star of approval since it comes with a backup utility that is easy to navigate and setup. If used in RAID 1, the My Book Mirror Edition not only makes an external back up of your data, it places the data on two drives within the My Book, giving you three copies total. Your important data is truly safe at that point from catastrophic hardware failure.

Can you really put a Dollar amount on your families collection of digital pictures? As someone who has actually lost several years of pictures, I can tell you that you can't, but I can say what the cost of it not happening is. The Western Digital My Book Mirror Edition can be had for around 399 in the U.S. - It is really a small price to pay once you consider the data being saved. This is true for both home users and business professionals; just exchange the word picture with client list or work documents and it all reads the same, data that you never want to lose.

For enthusiasts looking for additional features like eSATA or Ethernet connectivity, the Mirror Edition is not for you. USB 2.0 has not become slower, your worlds are moving along faster, but Western Digital makes a My Book for you. The Studio Edition and Studio Edition II both use USB 2.0, FireWire and eSATA, giving you access to your data just a little faster. Large file transfers would benefit from the Studio Editions, but most home users keeping several small files such as pictures and music will not notice a speed increase. The My Book World Edition and World Edition II have network connectivity, effectively making them My Book NAS devices and are geared for multi-users or owners of home networks where two or more systems can access the data.