An American in Paris, adapted by writer Craig Lucas and directed and choreographed by a member of ballet world royalty, Christopher Wheeldon, is a decidedly uneven affair. It wants to be part serious musical (the darkness of Paris after World War II and the Nazi occupation), part musical comedy (three guys in love with one girl!) and part contemporary and ballet dance show. Call it a ballet-sical (mullet doesn't quite work). Whatever it is, it doesn't quite work.