Immersion is part of any human experience, whether it is governed by the surrounding contingent world or by artificial, virtual spaces. In the cultural sector, immersive technologies are increasingly employed in contemporary artworks, installations, exhibitions and live performances. In this paper, we present and compare four multi-user interactive digital art installations, which are characterised by their varying degrees of technical immersivity (VR headsets, 360-degree space, video wall with floor projection, or sphere projection), their sensing capabilities (hand and head tracking, centre of gravity and joint tracking, motion tracking and multi-touch), their inherent interactivity (single or multi-user interaction, human-machine interaction), and the supporting stimuli (audio, visual, or tactile). These installations were exhibited in different public environments (art gallery, third place/cultural centre, shopping mall, museum), where the subjective user experience of 532 volunteers was studied along different immersion factors (spatial presence, affordance, enjoyment, and cybersickness among others). The impact of user characteristics like gender, age and prior experience with immersive technology was also evaluated. While spatial presence increases with the technical immersivity of the installation, the results suggest that factors like affordance and realness are more impacted by aspects such as interaction design and installation aesthetics. The evaluated user characteristics were found to have little or no impact on the immersion experience.