It also makes a huge difference if they are impacted or not. If they've grown in, it's no more painful than having any other tooth pulled. If they're still impacted, it's actual surgery, with much blood, and leaves you with with four large, gaping holes in your gums.
Mine were all four, impacted. Hence the swelling. I also had to have a follow-up surgery because I developed an infection. Pretty nasty.

