Do they work correctly?
Western Digital's self-branded external drives seem prone to weird behavior. Western Digital says they're not bootable, and a quick dance through Google for terms like "MyBook" and "LUN 0" suggest that Western Digital may have done something rather odd putting these things together.
For example: http://forums.bombich.com/viewtopic.php?p=44639#44639
As the user "baltwo" says there, "What they're really saying is we've got our little controller set up as LUN 0 so we can run our crappy button board and safe removal tools, instead of directing LUN 0 directly to the internal HD. That's also why they can't disable their disk sleep feature."
Do these new drives suffer the same problems? If so, thumbs down.