I ordered one of these when western digital announced them a few months ago, it's basically a 1tb laptop hard drive. and a bulky plastic case.
Firstly, the cable layout is frustrating, and requires bending the cables in such away that makes closing the case a pain.
Secondly, the software is very unimpressive, I had the system just stop responding several times, the windows client is rather underwhelming as well.
I just see no real advantages to say combining my own raspberry pi with a WD passport.
Other than the plastic box.