What mattc said, plus I find it easier to mentally interpret a template string than a concatenated string.

Template Strings, Well the template strings get's evaluated to this.name + 's age is ' + this.age; anyway. The reason I used it was because this kata is about the new JS2015 standard which is where the Template Strings were introduced so I personally found them appropriate to use.

${this.name}s age is ${this.age};
What do you call this notation, and why use it over:
this.name + 's age is ' + this.age;