It keeps randomly speeding up and slowing down while I'm playing, which throws the music off timing and makes me crash. I'm pretty sure it's a result of the app trying to load ads in the background, so I'll probably just buy the full (ad-free) version eventually. If I hadn't been playing the full version for such a long time on Kindle Fire devices, I would probably hate this app because of the speed bug. Closing all of my other open apps helps, although it's annoying.