Only ever had positive experiences with alcohol. Or any negatives have only been so minor as to not be memorable. Absolutely no alcohol-based regrets.
My time as a student and in my 20s was enhanced by really great, fun/funny times drinking with friends, my 30s was a very low drinking decade, with a young family, and approaching my mid 40s it's really just enjoying a single fairly large drink maybe 2 or 3 times a week to relax with. About 12-14 units a week, probably. I ponder on the health aspect, but I'm not feeling any negatives in that respect.
Certainly, a handful of friends have had differing relationships and reactions to alcohol, though I've not known any full blown alcoholics.