I love cloud backup, frankly. I use CrashPlan. Good client, easy backup, unlimited storage for about $3 a month. Nice thing is that all files are encrypted (blowfish), and you can choose just how private you need them to be. You can have your account password only as required to decrypt (which they of course have, and if they were feeling nefarious, I suppose they could use)...you can have a private password that is used to encrypt, that they DON'T have.
Or, if you're really paranoid about others possibly having access to your files, you can choose when you do your backup to have an encryption key generated locally, which you then store (and should definitely back up)....and they never have it, so you simply send encrypted data to them that can't be unlocked by anyone but you. Of course the downside is that if you lose your key, your data is garbage, but that's why they offer the other options. That encryption method is basically impossible to crack, and they can't look at anything. I tried a bunch of them when I was trying to decide where to go, and CrashPlan seemed the best to me...had the best client (you can choose what folders and files to backup...a few of these services don't allow that...it's all or nothing), good prices, good service reports, and if your initial backup is enormous, you can have a hard drive sent to copy files to and send back as your initial backup.
If I need to recover files, I can go online through the website to download all or part of the backup (can select individual files), or even pull them down on my phone or tablet. If I lose my whole PC, I can order a hard drive with my backup on it so I don't need to download 1.4 TB of data.
I have 1.4TB backed up (I also have a few off site storage solutions). I'm a photographer with hundreds of thousands of images, and it's really nice to know they are backed up off site within a day of a shoot, without me having to think.