I love the stuff and wouldn't see a dentist that didn't use it.
I've had several teeth pulled, bridge work, crowns, etc. They start the nitrous oxide right away and it is wonderful, it makes me so relaxed and if the dentist can't get to me right away (sometimes he goes back and forth between patients) I swear I fall asleep.
I still get the novocaine of course, and my dentist even puts a little bit of numbing gel on the spot first where he is going to give the shot. They put it on a q-tip (or something similar, not totally sure) and dab it on the spot then have you sit there with your mouth closed to keep it in place for a couple of minutes and then I don't even feel the needle when they give me the shot.
We do not have dental insurance, so we pay for everything ourselves. Our dentist does not charge extra for the nitrous oxide, so that's nice of him to do.
I even like to have the nitrous oxide when I have a cleaning and they don't mind letting me have it for that.
I think my excessive fear of the dentist started when I was in 4th grade, I had a cavity and my dentist then (thankfully he is retired!) said it was small enough that I didn't need novocaine. I was petrified he was going to hit a nerve, so I sat there clutching the arms of the chair. He did hit the nerve, twice. Kept saying "just a little bit more." So, dealing with that when I was just a child was horrible.