Bought one for myself and each of my family members for Christmas... A funny gift that has gained some serious love and respect in our household. Many nights this Christmas break were spent watching movies and playing games in these things! I'm a 25-year-old med school student living in Cleveland, and I obviously brought it back to school with me. Love lounging around in it, and it's great for studying. Current temp is -22 degrees in Cleveland (a record low), but I'm toasty warm! Mom and dad will wear theirs snowmobiling at the cabin. Younger brother (college senior) says he'll will wear his out to the bars with a Santa hat and not pay for a single drink all night!
I have been buying Union Suits for all members of our family (adults), and find that I need to buy them 1 (one) size smaller than I usually buy their clothing. Our females are usually mediums, but for the union suit, if I buy it in a SMALL, it fits them better. This goes for the Men's Sizes also. I buy ONE SIZE SMALLER THAN THEIR NORMAL SIZE. I guess this means they run a little large. My entire family love their LL BEAN Union Suits!
I love this for sleeping; all I need to do is add socks and I'm warm all night. The back slit isn't designed well to be of practical use, and one button barely keeps it closed. I'd just as soon not have the back opening at all, since I have to unbutton the whole thing down the front to use the bathroom. I don't know if an actual flap would suffice, but this doesn't work for - well, anything. I'm not sure I'd want to "go commando" in these anyway without a better lining for and construction of the crotch. The fit isn't superb, but I'm not looking for fashion, and it works for me.
My 1st layer of defense when going out to play in the winter day's & night's especially when snowmobiling. My spouse has had a few pair and decided I needed a pair of my own.