We've got one, albeit with Windows PCs only. It's actually our second. The first failed, and I spent a while mucking around with an obscure thing you can do with taking the disc out of the case, and reformatting it and reinstalling the software from Linux. I forget the details. Anyway, it worked for a bit, then failed again.
I have to admit to buying it as the easy route - you can pick them up in various shops. The name is daft - the point about cloud computing is surely that there are so many servers all working together, that any question about where your particular service is running becomes at best hazy. So when I can say, "It's up on that shelf in the hall", then calling it cloud is stupid. And yes, I find that the software designed to make it easy to use also makes it hard to do anything else with it. So I'm not really sure why I bought another, when I could have bought a NAS.
The other thing I don't really get is that it can, I think, work as a media server. Since I don't really want a media server, I've not investigated it much. But the idea of running any live service from your backup device seems contradictory to the point of futility.
Edit: I'm rather glad of this thread. It's made me check and notice that our ancient WD SmartWare is out of support, and we should
use something else with the drive. I'm deciding now between their WD Backup software now, and the custom version of Acronis, which might be better; I know that has a reputation. Sorry, Windows-only I think?