This paper presents guitARhero, an Augmented Reality application for interactively teaching guitar playing to beginners through responsive visualizations overlaid on the guitar neck. We support two types of visual guidance, a highlighting of the frets that need to be pressed and a 3D hand overlay, as well as two display scenarios, one using a desktop magic mirror and one using a video see-through head-mounted display. We conducted a user study with 20 participants to evaluate how well users could follow instructions presented with different guidance and display combinations and compare these to a baseline where users had to follow video instructions. Our study highlights the trade-off between the provided information and visual clarity affecting the user’s ability to interpret and follow instructions for fine-grained tasks. We show that the perceived usefulness of instruction integration into an HMD view highly depends on the hardware capabilities and instruction details.