New Twiddle

controllers.application.js

import Ember from 'ember';

class MyModel extends Ember.Object {
  constructor() {
    super();
    this._first = "Ricardo";
    this._last = "Mendes";
  }
  
  get first() {
    return this._first;
  }
  set first(v) {
    this._first = v;
    this.notifyPropertyChange('fullname');
  }
  
  get last() {
    return this._last;
  }
  set last(v) {
    this._last = v;
    this.notifyPropertyChange('fullname');
  }
  
  get fullname() {
    return this._first ? (this._last ? this._first + " " + this._last : this._first) : this._last;
  }
}

export default class MyController extends Ember.Controller {
  init() {
    super.init(...arguments);
  	this.appName = 'Ember ES6 Demo';
    this.model = new MyModel();
  }
};

templates.application.hbs

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

<h3>{{model.fullname}}</h3>

<div>
first: {{input value=model.first}}
</div>

<div>
last: {{input value=model.last}}
</div>

twiddle.json

{
  "version": "0.11.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.10.2",
    "ember-data": "2.11.0",
    "ember-template-compiler": "2.10.2",
    "ember-testing": "2.10.2"
  },
  "addons": {}
}