You have multiple ways to show the content properly:
<p> {{ content.content }} </p>
<p> {{ model.content }} </p>
{{#with model}}
{{content}}
{{/with}}
http://emberjs.jsbin.com/pivet/1/edit
When you return an array or object in your model hook, Ember would auto-generate an ArrayController or ObjectController for each case, and assign your model content to its content property.
In your case, an ObjectController inherits of ObjectProxy which forwards all properties not defined by itself to its proxied content property, however the content property is not proxied.
Because of this proxy ability, you could read data in both formats:
{{model.title}} === {{title}}
But, it does not work in your content property.