It depends a lot on the style, size and placement. Generally speaking, stick and poke tattooing is surprisingly quite soft. A friend of us described the sensation as having a repeated cat scratch sunburn, which honestly isn't entirely inaccurate.
Most of the people who have tried both stick and poke and machine tattoos have said that stick and poke tattoos hurt less, and some say that hurts way less. It's far less invasive than a machine tattoo, which means the skin heals much quicker too. However the pain often depends on the particular area being tattooed - some areas will hurt more than others.