Linode additional storage

Hi, I am looking for an online storage for my Linode server. As I have read on this forum, some users are suggesting Amazon S3. I would like to ask for everybody's opinion who has used Amazon S3 before availing it's services. Any other options recommendations and suggestions will be greatly appreciated. Thanks in advance for your help.

My objectives is

• To have an extra disk space to put my client's sensitive files into.

• Secured, only the admin can access it, I won't use it as an online photo gallery.

• If possible, it can be accessed as a local drive via ssh, an API or drive mapping.

As of now I have a lot of options but I am still reading reviews about it.