Terrible experience with basic (free) account. Syncing process made my average spec PC run slow for hours. Afterwards opening some but not all files and folders on PC was blocked. When using dropbox, got constant annoying popup. On uninstalling it, made a mess of the documents folder and removed all desktop shortcuts. Still not sure if all my files are where they should be. Would advise backing up files somewhere else before using if you want to risk it.
