I am not a big fan of clicker training it has to be said....if you can train your dog using praise, enjoyment, fun and contact then do it that way!
It is a great way to stretch a clever dog or to reward a dog that is working away from the handler. BUT the basics have to be in place before you even try this method. I know this is not what the people selling this method say but imagine.... Your dog is clicker trained, it sees a child, squirrel, racoon, other dog, cat, mouse, rat.... that it wants to run off it's patch, protect you from, play with, investigate....how will you stop the dog?
Not by clicking, I promise.

Clicker training has it's place.
Do not let anyone tell you this is the only training you need for your dog.

The first part of clicker training is to get the dog to associate the click with a treat. So if the dog hears a click it knows a treat is on the way. Very useful to the owner on a tracking course or an agility course...
Although it has to be said that handlers and dogs enjoyed both long before clickers came along.

This is also the long established training method for dolphins and whales in captivity - a whistle often takes the place of a clicker - and how are they going to stop a behaviour that isn't wanted?