The aim of the purposed long-term study is to examine user experience and usability of a very popular app with a user-reported critical incident method. 20 Facebook power users are requested to interact with the Facebook App on their personal smartphones for two weeks. Whenever they encounter a positive or negative experience, it should be reported with predefined items. All participants could report with paper-and-pencil or use the movisensXS App. 10 participants get generic feedback on completed reports (e.g., remaining study time); while 10 participants receive personalized feedback (e.g., number of completed reports). We want to explore in which experience situations participants prefer (1) the smartphone as reporting tool and (2) different media (requested textual comments, optional photos/drawings/screenshots and voice recordings) to describe their experience. We suppose a low drop-out rate based on the flexible way to report experiences (i.e., media, digital or analog report). In addition, we assume that the personalized feedback group has a higher compliance as well as acceptance and a lower reactivity than the generic-feedback group.