I haven’t been impressed by their published data, at least compared to the mRNA vaccines.
They looked fine for most things, but I saw some less than stellar efficacy data for the South Africa variant that was a bit concerning. This one in particular was not particularly encouraging: https://ir.novavax.com/news-releases/news-release-details/novavax-covid-19-vaccine-demonstrates-893-efficacy-uk-phase-3
Even if those results are confirmed, their overall efficacy is still good enough to be a useful tool (e.g. 89% in UK Phase 3).