Like Werga said
(1)Music (2)Medals (3)Leaderboard , a background changing would be nice too, or you could make levels for the backgrounds, personaly i would like a bit of story , either an into or something in the "Author Comments", just to give you a reason to play.

Okay lets see

Fun and simple concept a tad repetitive could use some music, medals and a leaderboard maybe a background change would be nice and yeah that's about it! Talk about short sweet and to the point!