Virtual try-ons have recently emerged as a new form of Augmented Reality application. Using motion caption techniques, such apps show virtual elements like make-up or accessories superimposed over the real image of a person as if they were really wearing them. However, there is as of yet little understanding about their value for providing a viable experience. We report on an in-situ study, observing how shoppers approach and respond to such a “Magic Mirror” in a store. Our observations show that the virtual try-on resulted in initial surprise and then much exploration when shoppers looked at themselves on a display that had been set up as part of a make-up counter. Behavior tracking data from interactions using the mirror supported this. Survey data collected afterwards suggested the augmented experience was perceived to be playful and credible while also acting as a strong driver for future behavior. We discuss opportunities and challenges that such technology brings for shopping and other domains.