Due to privacy concerns, I don't put everything in Dropbox. But most of what I do doesn't need to be that protected. And I do keep somethings in Dropbox that have been gpg encrypted.

I live in a office and work environment with windows that people can look in. I don't much like people staring in, but I am also not about to keep the blackout curtains drawn at all times.

I do wish that there were other more secure options than Dropbox, but the combination of easy of use, price, third party support, and collaboration make Dropbox hard to beat.