Google for 'crashplan data loss', and you'll find a few anecdotes. The plural of which isn't "data", but it's enough to ensure that I wouldn't use it for my own important data if I wasn't running two backup servers of my own for it. Even then, I'm also replicating with Unison to a ZFS filesystem that has auto-snapshots enabled. In fact, my Crashplan backups are on the same ZFS setup (two machines, two different countries), so I should be covered against corruption there as well.

Suffice to say, I've been burnt in the past. That seems to be the only way that anyone ever starts spending this much (that is, 'sufficient') effort on backups.

E.g. http://jeffreydonenfeld.com/blog/2011/12/crashplan-online-backup-lost-my-entire-backup-archive/

All of that said?

I'm paranoid. I wouldn't trust a single backup service, even if it had never had any problems; I'd be wondering what they were covering up, or if they were so small, they'd likely go away.

Crashplan is probably fine. Probably.