The ability for users to be able to access their own files from anywhere without having to go into our system was really helpful when we were trying to get new employees up & running quickly with no IT help needed! It's not so much as what I disliked about it but more how easy the interface makes working remotely or using multiple devices very simple since you can always find your file where ever you need them at any time.
We've been solving problems related to being disconnected while out traveling/working remotely which has allowed us to keep productivity high even though there are times we don't have direct internet connectivity via wifi / cell phone data plan etc.