I love the sewing retreat, and yes all the things you mentioned happen, but even so they are so much fun, so newbies to retreats don't get frightened off, you'll love 99% of it.
My biggest problem is the heat, I try to find the coldest spot in the room because some just keep pushing the heat up too high, the people quirks I can put up with but being too hot just ruins it for me. I always wear lightweight summer clothes no matter the season.