[itimpi]

Public mean exactly what it says so you need to be careful of what you put in there. Having said that the URL is not exactly guessable so as long qas you do not give it out it is unlikely that others would find it, but I would certainly not want to put any really sensitive information in a public folder. However it is extremely convenient way of allowing selected users access to less sensitive information with the minimum of setup required.

I think that the level of control of the security of files that are visible via a web browser is one area where the different web storage services differ. One also tends to find that more is offered on paying accounts than free ones. One needs to decide what your requirement actually is if this is an important factor in choosing between them.

I personally host my ebook collection and calibre2opds catalogs under an apache web server so that I can get individual username/password control (i.e. more granular than the Calibre content server). Apache would allow more stringent secutiry if I wanted to set it up but I have not bothered with that yet but I do monitor the web logs for anomolous access.