It outputs HTML5 ready to go. For other platforms where you don't want the customer using the browser to access it, you need a wrapper.
Windows 8/8.1 has it's own, as does Firefox marketplace, Amazon, and Tizen.
But Android and Apple are still 3rd party, and the two most integrated are actually still in development, so if your project is going to take awhile, you may be fine. (we've come a very long way the past 6 months, and Construct2 updates nearly weekly.)