Skin treatment device comprising: - a housing whose shape and size are suitable for being held by a human hand; - a treatment action performer associated with the housing for performing a treatment action on a user's skin; - a speed sensor for sensing a relative displacement speed between the housing and the user's skin in a device displacement direction parallel to a surface of the skin; - a speed feedback signalling device comprising a signal generator for generating a signal perceivable by a human; - a control device provided with an associated memory containing information defining a tolerated displacement speed range, the tolerated displacement speed range having an upper threshold and a lower threshold; - wherein the control device is coupled to receive an output signal (Sv) from the speed sensor and is coupled to provide a control signal to the speed feedback signalling device; - wherein the control device is adapted to compare the speed sensor output signal (Sv) with said upper threshold and with said lower threshold, and to control the speed feedback signalling device such as to generate a first feedback signal when the speed sensor output signal (S V) indicates that the relative displacement speed is higher than said upper threshold and to generate a second feedback signal when the speed sensor output signal (S V) indicates that the relative displacement speed is lower than said lower threshold; characterized in that the control device is adapted to monitor a parameter indicative of a degree of a user's ability to move the skin treatment device at a correct speed; - wherein the control device is adapted to set a relatively large magnitude of, or increase the magnitude of, the tolerated displacement speed range if said parameter indicates a relatively low degree of said user's ability; - and wherein the control device is adapted to set a relatively small magnitude of, or decrease the magnitude of, the tolerated displacement speed range if said parameter indicates a relatively high degree of said user's ability. - a housing whose shape and size are suitable for being held by a human hand; - a treatment action performer associated with the housing for performing a treatment action on a user's skin; - a speed sensor for sensing a relative displacement speed between the housing and the user's skin in a device displacement direction parallel to a surface of the skin; - a speed feedback signalling device comprising a signal generator for generating a signal perceivable by a human; - a control device provided with an associated memory containing information defining a tolerated displacement speed range, the tolerated displacement speed range having an upper threshold and a lower threshold; - wherein the control device is coupled to receive an output signal (Sv) from the speed sensor and is coupled to provide a control signal to the speed feedback signalling device; - wherein the control device is adapted to compare the speed sensor output signal (Sv) with said upper threshold and with said lower threshold, and to control the speed feedback signalling device such as to generate a first feedback signal when the speed sensor output signal (S V) indicates that the relative displacement speed is higher than said upper threshold and to generate a second feedback signal when the speed sensor output signal (S V) indicates that the relative displacement speed is lower than said lower threshold; - wherein the control device is adapted to set a relatively large magnitude of, or increase the magnitude of, the tolerated displacement speed range if said parameter indicates a relatively low degree of said user's ability; - and wherein the control device is adapted to set a relatively small magnitude of, or decrease the magnitude of, the tolerated displacement speed range if said parameter indicates a relatively high degree of said user's ability.