P.W.
N.,
I had a root canal done on a molar that broke about 6 or 7 years ago, then had a crown put on it. I have not had any problems with the tooth since. I was mortified because I heard horror stories. To my surprise, it was not painful. Like another person said, the most inconvenient thing is that your mouth is propped open with some plastic device and you have to have it done in multiple visits.
Like with anything, if the dentist is good at what he/she does, then the experience will be pleasant.