This paper reviews how empirical research on User Experience (UX) is conducted. It integrates products, dimensions of experience, and methodologies across a systematically selected sample of 51 publications from 2005-2009, reporting a total of 66 empirical studies. Results show a shift in the products and use contexts that are studied, from work towards leisure, from controlled tasks towards open use situations, and from desktop computing towards consumer products and art. Context of use and anticipated use, often named key factors of UX, are rarely researched. Emotions, enjoyment and aesthetics are the most frequently assessed dimensions. The methodologies used are mostly qualitative, and known from traditional usability studies, though constructive methods with unclear validity are being developed and used. Many studies use self-developed questionnaires without providing items or statistical validations. We discuss underexplored research questions and potential improvements of UX research.