Even if Shawn Mendes emerged via modern means–covering Justin Bieber on Vine– there’s something charmingly vintage about him. His boy-next-door earnestness and puppy-love tales are as old as rock & roll itself, just like his acoustically driven, boldly defined melodies. By applying these qualities to 21st-century rhythms–an R&B strut on “Stitches” and “Something Big”, springy folk-hop on “Air”–his slick pop proves invitingly fresh yet reassuringly classic.