The worst part in my experience was actually getting numbed. You can't see the needle going in so a lot of people with needle phobias won't have any problem, but for me the feeling of a needle is repulsive. After that it was smooth sailing, just a bit boring.
The pop culture reputation of dentists as literal torturers is pretty outdated. Medicine has improved a lot in a short amount of time. Just look up reviews before picking your dentist, and don't cheap out if you can help it.