I had a My Book (500Gb) for quite a long time and later on bought myself a My WorldBook (1Tb). It was fun while it lasted: after a while the MyBook didn't work for some reason; even copying a 1Mb file would take minutes (just for context: my computer and the MyBook were hooked up onto the same switch, and other network related functions worked without any issues).
Eventually I opened it up, took out the HD, learned about the Linux OS and ext2 (or ext3, don't remember) filesystems and then copied all my data from it. Right now this same HD sits inside my FreeBSD server, now UFS formatted, and it works just fine. So much for reliability.
I still have the WorldBook but I don't dare to copy any data onto it because I fear for the worst. So it's read-only for now. I'll probably end up opening it up and taking out the HD as well, that will be the end of my My Book endeavors.