If you're looking for a new experience and you're a hardcore fan of the rhythm genre I say give it a shot. If you're looking for a true RPG experience or a deep challenging rhythm game, search elsewhere.
SUPERBEAT: XONiC recaptures the magic of peak rhythm gaming bliss. Excellent music, outstanding production values, and fantastic gameplay make this the full package. Fans of the vita version will find plenty to love, and newcomers will be enthralled.
Overall I enjoyed my time with Deemo. The story is heartbreaking, the art is interesting, and the music is outstanding. Personally I'd recommend giving the game a shot on the phone, and if you find yourself hooked, invest. Don't expect much new in the field of rhythm gaming from Deemo, but it's fun and familiar, and a good little time waster. If nothing else, watch the cut scenes if you can and enjoy the story.