Agreed, groups are a huge deal. Once I figured out groups my FB use changed dramatically. Now I'm on there all the time, my family and friends don't see what I'm doing unless I for some reason joined a public group, and miracle of miracles, you can even find file downloads in these groups and the search functionality works pretty well.

Facebook was in my no-thanks bucket for a long time, but that has really changed and it didn't involve any significant privacy compromises beyond the usual ad-sales stuff.

By the way, there are a LOT of people using assumed names in these groups. Some of them get reported and return to unleash their annoyance on the rest of the group for "whoever did that". It's a really awkward aspect of the experience IMO.