For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
Dropbox - Online Sync and File Sharing
Lassie Smoke - The modern way to quit smoking
Google Drive - Access and sync your files anywhere
Smoke Free - Virtual "Quit Smoking Buddy" in your pocket
Mega - Secure File Storage and collaboration
Quitbit - A smart lighter and app to help smokers quit (pre-order)