Our company uses it with Box.
The integration is pretty easy to use since it opens up a pop up window and you navigate to the folder/doc in which you are trying to attach. Once you save the attachment and click it to open it takes you to the Box preview window where you can open/edit/view based on the permissions you've set.
It was intuitive for me to figure out how to use so I would imagine it would be pretty intuitive for others as well.
I have linked a Box folder to my sheet once or twice. It was simple and I had not problems that I can recall
