I have been an Apple TV owner since the day it was released, and have nothing but good things to say about its quality, ease-of-use, and integration.
We had a free subscription for Hulu plus, and now my kids won't let me cancel it. It allows them to stream shows to their iPads after lights-out and watch all the Nickelodeon content their little hearts desire. I got duped.
Besides the streaming content, if you have iPhones you'd be foolish not to get an Apple TV as you can stream video and photos that you've taken directly to the TV without transferring any files. Just walk in the house, hit one button, and all the photos you just took are up on the big screen. And if you use photo stream, it's even better as you can share photos with family and friends. I created a photo stream for my kids grandparents at the moment I take photos on vacation and put them in the stream they can see it on there instantly.
Here's a good article comparing the two devices: