If using a Wiitar via WiitarThing and attempting to automatically map the controller using the "WiitarThing Guitar" preset, fret bindings are incorrect, whammy is set incorrectly and the tilt binding is missing, fret bindings 1-4 are set to bumpers/triggers (when they should be A B X and Y) and fret binding 5 is set to a face button (should be Right Bumper) and Whammy should be bound to Right Stick X but is instead bound to Left Stick X (or Y, can't remember). Tilt binding (should be Right Stick Y) is entirely missing.
All of these bindings can be redone manually but the automatic mapping is wrong, at least for me.