My first Brazilian definitely hurt but it wasn't unbearable. In some spots, I hardly felt it. Others were more painful, with the worst being the area on top of your pubic bone - I admit that hurt quite a bit. The esthetician will hold your skin taut when pulling off the strips, which helps - you can even offer to help her hold your skin taut as she works in different areas. I always take an anti-inflammatory, like Tylenol, an hour before the appointment. In terms of pain, I think it is the thickness of your hair that counts rather than the color. I've heard Brazilians are more painful for girls with coarser hair.
A few tips...Don't go when you are premenstrual (or menstrual) - you'll be more sensitive. Trim your hair before you go to about 1/2 inch long. You don't want it full length because that would cause unnecessary pain. If you regularly shave all your hair off, you'll need to let it grow out to at least 1/4 inch so the wax has something to cling to. I always wear loose clothing and panties without tight elastic, to prevent irritation from the friction caused by tighter clothing after the appointment. My esthetician says to avoid sex for 24 hours after the waxing because you don't want bacteria getting into the open follicles. (Easier said than done though.)
The good news is that while the first time can be quite painful, the pain lessens with each wax. I was thrilled after my first one - the pain was totally worth it. And now, it isn't a big deal. If you haven't had a regular bikini wax, you might want to try that first.