I have less hair on my back than doth Bozack but I still put the Nair to it when I was in college.
My unwanted-hair dilemma includes the back of my neck, which is solved easily enough with a Braun and a willing girlfriend with a steady hand, but the back hair thing was a Problem that I had to solve on my own. I must not have been as careful with the Nair as I should've because I got some on the top of my shoulders and it removed all the little, normal, non-offensive hairs that everyone just kind of ignores.
The resultant sensation was hell of strange - my t-shirts were actually touching bare skin without the tiny hair buffer zone to cushion them. It was like being constantly stoned, always aware that I'M TOTALLY WEARING A SHIRT, MAN, AND IT FEELS SO HEAVY!!
So my warning would be to watch where you put that stuff. It takes off ALL the hair it touches, not just the nasty ones, and you'll be left with patches of crazy sensation. Otherwise it was satisfactory and lasted much longer than I expected.
I've heard that this phenomenon motivates many women to wax "down there," a factual fact that I include only out of TOUAMB obligation to Educate.