The recent introduction in the market of low cost yet high fidelity head-mounted displays with stereoscopic 3D perspective such as Oculus Rift opens the door to novel virtual reality experiences for gaming. However, QoE metrics and methodologies for this kind of platforms are still unexplored. In this paper, a comparative study on how these novel displays impact gaming QoE with regard to conventional 2D PC screens is presented. Through an experiment where we invited 22 users to play with a virtual forklift driving serious game in both environments, we demonstrate that Oculus broadly increases the sense of immersion in the 3D world as well as perceived game usability. Affective factors are also deeply impacted by this platform that shoots up amazement, astonishment and excitement levels. Nevertheless, a worrying aspect is the high percentage of persons that report feelings of nausea after wearing the goggles.