New Twiddle

application.controller.js

import Ember from 'ember';
const { inject, computed } = Ember;

export default Ember.Controller.extend({
  myService: inject.service(),
  appName: computed.reads('myService.value')
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

services.my-service.js

import Ember from 'ember';

export default Ember.Service.extend({
  init() {
    this._super(...arguments);
    this.value = "initialized";
    setTimeout(() => {
      this.set('value', 'Later');
    }, 3000)
  }
});

twiddle.json

{
  "version": "0.4.10",
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/1.13.11/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/1.13.9/ember-template-compiler.js"
  }
}