I was a beta tester for the Amazon Video On Demand on the Roku and I can say I am happy with the service. I really think the Roku is going to become the defacto winner over AppleTV and Vudu and all the other TV devices because 1 it’s $99 compared to AppleTV $229, Vudu $149 (w/0 wifi) and 2 Roku seems commited to adding other content partners to their device.
As somebody who has purchased and rented lot’s of movies and TV shows from iTunes I can tell you that I intend to switch to using the Roku/Amazon service. The Amazon model of allowing me to just stream the show to my TV vs. downloading them is much better IMHO unless you want them on your iPod. I am running out of space on my Mac and would really hate to loose all of that content when my hard drive fails or worse when my backup fails. With Amazon I don’t have to worry about it becasue they store it for me.
Apple could still change the game if they focused on opening up the AppleTV to other content partners(Netflix,Amazon,etc..) and made it worth the $229 by adding a Blu-ray or DVD player.