GlowWorm FW prevents applications from accessing the internet in ways that you have not explicitly allowed. Your email client can be restricted to your mail server. Your web browser can be restricted to the web sites that you visit. Rules can assigned to a particular user so that you can apply more restrictive settings for your children.
GlowWorm FW can prevent your computer from being useful to hackers while not being cumbersome to you. As you use GlowWorm FW and customize it to fit your needs you will find that it becomes less and less noticeable, while it continues to work in the background, protecting the security of your Mac.