I got the initial J+J in June 2021 and had some side effects but nothing serious or life threatening. It had already been "banned" at that point in my country but was still available from a private company so I went that route.

I didn't get any boosters, but I did get Covid a few weeks ago. I had fairly regular flu symptoms. I was out of commission with a fever for two days and was exhausted for a week afterwards, but no long-lasting symptoms. My fiancee had the same one dose and no boosters and also got Covid, and he had an easier time with the Covid (mild fever for a day and a cough for the rest of the week), but his sense of smell and taste are still off.