It's hard to compete with free. Google can afford to undercut Dropbox.
Clearly, if I was going to use the service as disaster recovery, I'd pay for dropbox. (I use dropbox for free right now)
Competing with Google is like competing with MS in '90s... a really hard proposition.
Depends on your circle really. For personal stuff, I make full use of google. However for anything business related my leash of trust would be a lot shorter. I'd feel much more comfortable to pay for a service that gives me someone to blame/sue should the response to a disaster be less than adequate. You really just don't get this with google.