I have been using Box at work and it is rather nice. It is fairly unobtrusive. Granted, I don't use the desktop integration just open stuff over the web page, upload files when I need. There is an interactive notes and presentation editing.

I think Dropbox's problem is mostly Google. I used Dropbox at home but once Google got their drive up to speed and it integrates with other things like Gmail and such, it is hard for me to justify using Dropbox. So I uninstalled it and just use Google for everything.