This paper investigates the effects of interaction level, framerate, field of view, 3D content feedback and previous experience on subjective User eXperience (i.e., presence, engagement, immersion, flow, emotion, skill, experience consequence, judgement, technology adoption) and objective usability in immersive virtual environment. Data were collected from a series of five sub- experiments (i.e., one for each influential factor) that involved a total of 152 individuals. The participants were asked to use the "Think and Shoot" immersive virtual environment and to complete a User eXperience questionnaire. Their subjective perceptions and objective measures were collected and analyzed. The results revealed that interactivity level and previous experience had an effect on subjective User eXperience and on objective usability. Framerate and field of view had an effect on objective usability. Finally, 3D content feedback had no significant influence on User eXperience. From these findings, key points for User eXperience practitioners are proposed.