Don't know of a key to advance to the end of a screen of choices, like the channel down key in Netflix which will advance to the end of the option on the current screen. Should have option other than left/right arrows that move one selection at a time.
Wish there was a longer time between episodes to allow you to get back to the menu before it starts spinning into the next teaser.
Back button vs. back arrow don't seem to be "noticed" all the time.
Prime's content is much better than Netflix but the interface needs a little work.