I had a root canal almost three years ago (actually, two root canals, on the same tooth, about two weeks apart.) I saw an endodontist for it, and I was terrified- it turned out to be nothing to worry about for me. I almost fell asleep during it. I didn't feel any pain, thanks to the novocaine. It was annoying to keep my mouth open for so long, but that was it. I went on a six-hour flight two days later. I was given Tylenol with codeine but didn't really need it; I had some pain for a few days after, especially due to the flight, but Advil helped. Unfortunately, my pain returned and the endodontist repeated the procedure in hopes that he had missed a bit. He found nothing.
More unfortunately, I'm having pain now, and will be having the tooth extracted. I was given the option to try another root canal first, but was told it probably would not work, and financially, can't swing the root canal and then extraction and implant. I wouldn't hesitate to do a root canal again on another tooth, though, as I found the experience to not be painful and not so bad. The extraction, on the other hand... I'm right back in that terrified place!