The stick is just a cheap alternative to buying another Fire TV if you wanted to connect to a different TV.Is the stick worth having when you've got the fire tv ?
If your just using one TV then you don't need both!
From my experience there isn't much between the Fire Stick or TV, however things like Ethernet and Optical audio may sway you to the TV.
The stick for most people though with good wifi is more than suitable and it gives you a nice saving from the fully fledged Fire TV.