I installed the update last night and my battery has been fine.
The updates did not re-enable himself, so it was okay for me.
I suppose using it to rent movies would be okay.
I would use the app, but the list of movies is limited.
It's unclear if you "buy" a movie what you'll be getting. If it were an AV file that could be copied and played to any device, then I would try buying a movie that I like.
Though I'm betting it's some DRM crap that you can only use on one device and can't stream to a TV.
I spend plenty at Amazon on MP3s, but I know what I'm getting and can do what I want with the files after I purchase the content.
I was actually thinking of trying the Blockbuster service out with Tron Legacy or Star Wars A New Hope, but they don't have either movie. Must be a licensing problem, I guess.