I purchased a Western Digital My Book World Edition II - 2TB model not too long ago and was quite surprised by the rugged looking device. In whole, the device was well packed and have an attractive external white casing. I tried opening the lid to access the internal drives... as you do fiddle with newly purchased items... I could not for the life of me get it open. A flaw in the design or just a problem with the one I purchased. Anyway, I know you can remove a failed drive for replacement, but the new drive must come from Western Digital in a proprietary mounting.
Setup is straightforward. While installing WD Anywhere Access, you give the drive a name, which becomes the URL for accessing its configuration menus. Good built in features and RAID 1/0 setup makes this model great for high volume file storage with the peace of mind that your data is safe and secure. I tested the data transfer rate of a 1.7gb folder containing a few hundred files and it too just over 9 minutes to complete.
Overall a good device with excellent features and ideal for home or SOHO use.