Utilising biometric data has become an increasingly active area in the video games user research community, and a number of academic papers have been published introducing various biometric based analysis techniques in video games research. This paper aims to quantify the value of biometric methods as an addition to traditional observation-based user research methodologies, and their respective contributions to the production of formative feedback during the development of video games. Our results show that observation-based techniques can expose the majority of issues relating to usability, however the biometrics-based approach enabled researchers to discover latent issues in related to players’ feelings, immersion and gameplay experience and, in certain categories of issue, reveal up to 63% more issues than observation alone.