I had it done a few years back, my hair is fairly wavy but not super curly. I got it for free, was stopped in the street and asked to be a hair model for a demonstration thingy. It worked fairly well, i still had a bit of a wave, but I liked that, it lasted about 2 years, but that was because my hair grows out straight and then goes wavy down the bottom. I had an awesome time getting some killer asymetrical haircuts that would have been wasted on my wavy hair.

Eat a big meal before you go in, it takes aaaggggeeessss, lol.