It's crap. They are all crap.
The FireTV gives the same functionality as GoogleTV, AppleTV, Xbox, Wii, and my Samsung Home Theatre with "apps".
All of these things just provide little apps as a gateway to other services. In other words...you're paying to buy a device that lets you pay more for content.
I suppose if you don't already have a more powerful device like a gaming console, it would be worth it. However if you already own an Xbox or PlayStation, you're just throwing money away.