Undergraduate research experiences are being incorporated into degree programs with increasing frequency. However, there has been little study into their effectiveness in preparing students for research or into the learning gains that students realise from one or more research experiences. We surveyed science students in an elite, research-based undergraduate degree program at a research-intensive university. These students complete six research projects during their degree and we aimed to delineate factors that students perceive as leading to either good or bad experiences. Two factors stand out as contributing to a successful research experience: the supervisor, with students reporting both pedagogic and affective benefits of good supervision; and the feeling that they are doing authentic science. Surprisingly, given the research-intensive nature of this degree, the learning gains students report relate to both an appreciation of what research is like and life skills, such as time management, rather than scientific thinking skills. (Contains 6 tables and 2 figures.)