I have been using Dropbox for about a year. I find really helpful for storing my doc and file. I do travel a lot and have to deal with different type of marine equipment. Each of them have different model and manual. Having Dropbox is a great tools where i can download my store doc anywhere as long as i have internet connection.
You can also share your file with your colleague. Update and edit report that your colleague at the office update. This feature is very important as you and your friend can update one doc easily.
There are several ways that you can upgrade from 2 GB free, you can invite your friend to register and install Dropbox. You can also upgrade to dropbox for business.
So it will sync update on all your gadget.
Mostly I use Dropbox to backup my important files and photo. if anything happens to my pc or laptop, I can always can sync it back to my new pc or laptop. So no need to worries.