My back isn't VERY hairy, just thin hairs that come down from my neck. I got them done, didn't hurt but was red for a few days and I got a few spots. Apart from that it's fine.
i used wax strips on my boyfriend's back and he screamed like a little girl. apparently now though you can get veet hair removal mousse for men... less screaming certainly. waxing must be much sorer for men than it is for women. ahem.