I felt pretty lousy for a little over 2 days. Had a low grade fever. Maybe a little worse than my Pfizer vaccinations, but nothing I couldn't handle.
I wonder if they're going to come out with an Omicron-specific booster? (Both Pfizer and Moderna are working on that, but by the time they go through all the regulatory hurdles, we'll probably be past the Omicron wave. Sigh.)