Optimum is not available in Australia but as far as I can see it seems to be similar to a public WiFi system.

As far as security is concerned, above I did not mean that a hacker could *physically* "read over your shoulder" when you are using your tablet to check your e-mail or FB accounts using a public WiFi system at the coffee shop.

What I meant was that, because of the security vulnerabilities in some tablets, a hacker could *electronically* "read over your shoulder" - ie, steal private things about your e-mail/FB accounts using the communal public WiFi system at the coffee shop.