If you are an admin, you don't want users circumventing your security procedures. I know I do not like users pulling files down from disparate sites; but then it is OK for us right? Dropbox is one of those storage in the cloud solutions that could be deemed a security risk. It can also create more chatter on the local LAN if you have configured it for "Lan Sync" ( see this Link for what that is); but more than once it has saved me not only a lot of work, but actually helped me be more efficient working for a customer.
I was trying to install Spiceworks for a customer at a remote location but downloading to the server which I was connected to via vpn and RDP, would somehow corrupt the download. I had the file in my Dropbox, so I fired up the browser at the remote server and downloaded from there. In minutes I was up and running.
I know, I know, but it worked and I know what I am doing don't I? Well, in any case Dropbox has allowed me more than once to by pass firewalls and security to do good. Just be careful, because in the hands of a black hat, it definitely can be bad.