Mobile platforms and applications are an exciting and important phenomenon in today's software and business world. They are being woven into the fabric of daily life faster than expected. Continuous collection of user feedback enabling the improvement of platforms and applications becomes critical to support the continuous evolution of mobile systems. Particularly user feed- back is needed to provide systems that best fit user needs. We have designed a mobile feedback approach, which enables users to document individual feedback on mobile systems in situ. This information can then be evaluated and used as new requirements by developers. Based on this solution we have developed a feed- back app for two different mobile platforms. Furthermore, we have conducted a study with smartphone users applying this ap- proach and communicating feedback on a mobile platform and pre-installed apps. The study revealed that users were able to give individual feedback and that a large amount of this feedback was considered to be useful for mobile system improvement by a platform developer.