For those who've had WD MyBooks die on them, consider buying higher quality bare drives and dropping them into a well-powered and -ventilated external enclosure. Frankly, I don't trust any manufacturer's all-in-one, off-the-shelf consumer solution -- there are simply too many compromises, most of which are not publicized at all (e.g. even something as simple as the specific model and specs of the drives). Much better to create a more robust external HDD solution on your own -- and it doesn't cost much more.
FWIW, I'm a WD fan -- I typically purchase their low-ish end models targeted for business, with 3 or 5 year warranty, and never buy the latest-and-greatest, biggest-and-bestest model. First generation runs of any high tech device -- especially those pushing the envelope, like increasingly huge HDD storage -- tend to have issues. I'm much happier buying slightly smaller, more reliable HDDs with a proven track record. Personally, I don't see much point in being an early adopter of any HDD pushing the limits in the my-HDD-is-bigger than-your-HDD game.
I have, on occasion, used WD's advance replacement service (both in and out of warranty) -- not surprisingly, since all HDDs fail eventually. At the first sign of trouble with a HDD, the advance replacement service allows me to receive the new HDD, transfer and verify my data to the new HDD (whether from the HDD going bad or a known good mirrored copy), then wipe the old one clean before sending it back to WD. Very easy, very convenient.