  The increasing availability and diversity of virtual reality (VR)
applications highlighted the importance of their usability. Function-oriented
VR applications posed new challenges that are not well studied in the
literature. Moreover, user feedback becomes readily available thanks to modern
software engineering tools, such as app stores and open source platforms. Using
Firefox Reality as a case study, we explored the major types of VR usability
issues raised in these platforms. We found that 77% of usability feedbacks can
be mapped to Nielsen's heuristics while few were mappable to VR-specific
heuristics. This result indicates that Nielsen's heuristics could potentially
help developers address the usability of this VR application in its early
development stage. This work paves the road for exploring tools leveraging the
community effort to promote the usability of function-oriented VR applications.
