Like TM said, the Alexa app won't do voice commands on the iOS devices or the Fire tablets. The app seems rather useful, though flaky. I have no clue about the Alexa voice feature as I don't have a Fire tablet that is eligible to install it. The voice command feature on the Echo, Tap, Dot, and FireTV is very well done though. I rarely have to repeat commands, and when I do it is usually because I phrased the command awkwardly. I do have my Dot next to my TV and here lately there have been a lot of Alexa ads on TV so she sometimes gets confused when a TV ad blurts out "Alex, do [such and such]". I have to then say "Alexa, stop"!