I buy most movies and TV shows I watch on iTunes, but almost never day one movie releases. They usually show up later for a much lower price. Bundles are also a good way to save. I also use Hulu and Netflix but rarely. Hulu's commercial breaks are a real turn-off for me. I also find iTunes' quality to be superior to that of Hulu's. Netflix is great for watching some older titles and not to forget Netflix exclusives. I really whish there would be an Amazon Prime app for the ATV, but I am sure it will happen eventually. All in all I am pretty happy with the ATV. I travel a lot overseas and I really love being able to continue watching my shows no matter where I am. Luckily, there is no limitation for watching iTunes content in foreign countries, as long as you use your US Apple ID.
If you have an iPhone you can AirPlay what you're watching on the amazon video app.