No disc needed for Netflix. iTunes Store content available. All of your iTunes library on your PC or Mac will be available on your TV. You can put content on your iPhone/iPad and watch it via Apple TV. Price is much cheaper. I think the interface of the ATV is way better than Ps3. More intuitive, better for streaming content.
Only benefit I can instantly think of with PS3 is 1080p content. And games, of course.