Admittedly I went for a closed-source, non-free solution for my GF's backup needs. The data on her PC is critical for her income, but her work is not in any way computer related and with all the possible traps of a networked Windows system.. I was worried about her PC catching one of those ransom-malware type problems (she does occasionally get infected with some browser-hijacking malware, toolbars and the like). And for long periods I'm not there to look after her PC. So, some of those problems could make a normal backup corrupt as well. Thus, after testing the solution for a month I went ahead and bought a 4 year Crashplan subscription. It makes continuous (or as often as you want) backups, to the cloud, to local storage, local removable storage, other computers if you wish. With (if you want) non-expiring time travel. You can recover (also from another computer) any version of any file from any time. So, lots and lots of reduncancy, and versioned backups. It works very well as far as I can tell (I check on the backups now and then), is transparent, and runs in the background. It's easy to manage as well - we decided to make an extra backup once a week to another USB disk, to achieve that she only has to plug in the cable once a week, and the backup software detects it and makes the additional backup. Nothing to click, nothing to administer. Just plug in the USB cable, remove it later (e.g. in the evening) when the PC has gone quiet/to sleep mode.
It seems to be worth the money. It's a combination of cloud and local backup. The only issue I have with it is that the backup format, a kind of database as far as I can tell, isn't in an easily understandable format (in fact I have no idea about the layout), even if you turn off all the encryption (which you can do on a device basis).
We actually use that same software at work, but in another version of the product - all of the "cloud" is our local "cloud", nothing goes to their central server. Otherwise it's the same - set up a lot of rendudancy, then let it run automatically. I get an email once a week about what it backed up and to where, for my particular computers. I can have an even more local "cloud" if I wish. I guess all the rage will soon be a "Personal Cloud".. there's some Deja Vu here..
I'm constantly on the lookout for potential issues and downsides of course. And as far as my own storage is concerned I make all kinds of additional backups as well.. I lost some files back in the earlier years of my computer career, that will not happen again ever if I can help it.
-Tor