Performance isn’t great compared to desktop system and it doesn’t actually play mp3 files (Media are not supported yet), but having ability to run a java 8 application on $35 is amazing by itself!
If you want to try follow the steps on oracle site to install the image and then run:
$ /opt/jdk1.8.0/bin/java -Djavafx.platform=eglfb -jar MGPlayer.jar
* -Djavafx.platform is crucial as it let javafx work on OpenGL ES 2.0 embedded device
* I’ve installed java on my raspbmc image