most of the "smart TVs" and media players have a lot of overlap. so adding a different one probably won't add too many unique features.
(i've got 3 ways to watch netflix in the living room -- aTV, blu-ray player, and the TV itself)
with the aTV, you get 2 things you don't on the others.
1- access to the iTunes store for video rentals and purchases
2- airplay, which only applies if you have another iOS device (iphone/ipad).
If you're watching a video on a webpage on your phone, or looking at pictures, and want to share with friends, or see them bigger? you can send them to the TV.
some apps that you watch video in will airplay video directly, some wont, It all depends on the app developers and what they want to allow.
also some games let you use the aTV as a second screen, so the controls are on your phone, but the action is on your TV.