Tattoos effect the surface layers of your skin. The sensation is most often described as feeling like some one drawing on a sunburn with a pointed pen or a sort of continuous cat scratch. Nothing unbearable. 

Pain is subjective so there are varying opinions on this but the end point is that there will be a sensation and while on the whole its not overwhelmingly going to suck you will feel something. 

Everyone's bodies are different in how they process pain so there will always be someone who doesn't fit the mold but over all the rule goes that if you are ticklish or sensitive to touch there with out any work being done then its probably going to be more uncomfortable to get it tattooed than somewhere that isn't like that. Areas that are less painful tend to get more consistent impact in life.  Think about how the top of your thigh tends to be less sensitive than the back of them for example. 

Another common rule is that areas with thinner skin over the bone or the longer a session the more sensation may be present. 

Men and Women do have slight variations in where they report being the most sensitive to getting work done. For example Men tend to hate getting their calves done more than Women, while Women tend to report more sensitive to work on their hips and outer thighs then Men.