There is one piece of advice when using your own mp3's as tracks to play. The tracks must have an artist name and track name (and maybe the title can't contain the character "-"). I was lazy and my mp3 tracks that didn't meet these requirements caused the app to malfunction until it was reloaded. I'm not sure how long the fun will last with only 3 available songs and customized(not fully compatible) songs, but it definitely is the funnest Rhythm Game genre apps for Android OS.
Good Luck on your app search.