I attended a few years ago (28C3). Had a great time and gave my first (unofficial) talk ever there. Found people to be supportive and chill; maybe it had to do with the fact that I was rather young at the time. I don't know.

That said, it is frustrating that they don't release the schedule weeks ahead. I was seriously thinking about attending but did not go through because conferences these days tend to have far less technical content than they used to.