I feel 100% except the sore arm. I tend to get sore arms whenever I get vaccinated so this isn’t a Pfizer thing. Last time I had some boosters before traveling (remember that?) I had the same thing.
All my family in Israel has had their third dose now. I think it will be 6 monthly for now but I think natural immunity over time and probably slightly better vaccine formulas will see it pushed out to yearly boosters similar to the flu.