App wont open???

I used to have this app on my old iPhone 4 and it worked just fine apart from the occasional lag. It was pretty helpful for me as a musician. But I just got an iPhone 5s recently and now the app wont even open without immediately crashing! And the icon that shows up on my home page is not one that matches the one in the App Store. Something is messed up.

CosmicAttack about Virtuoso Piano Free 3