For me it has been the mental exhaustion, identity crunch and general angst that came with the second puberty. I knew to expect it, but I guess one can't really prepare for it in the end. At least I couldn't. But it's good in the end.
One of the most positive things about it has been that after a decade on sleeping meds, I could stop taking them and sleep just the same if not better.
Boob hurt! Mine have decided to go for it really fast and they're much, much larger than I would've dared to dream at this point. The touch sensitive nipples I did know to expect, but since they've come on this fast, I've been taken by surprise how much they hurt generally by just hanging in there and bouncing all over while moving.