A multimodal Positive Computing system with real-time feedback for public speaking has been developed. The system uses the Microsoft Kinect to detect voice, body pose, facial expressions and gestures. The system is a real-time system, which gives users feedback on their performance while they are rehearsing a speech. In this study, we wished to compare this system with a traditional method for practising speaking, namely using a mirror. Ten participants practised a speech for sixty seconds using the system and using the mirror. They completed surveys on their experience after each practice session. Data about their performance was recorded while they were speaking. We found that participants found the system less stressful to use than using the mirror. Participants also reported that they were more motivated to use the system in future. We also found that the system made speakers more aware of their body pose, gaze direction and voice.