How does nitrous oxide sedation at the dentist make someone feel?

Like you don't care: Nitrous oxide is an analgesic and not anesthetic. It does alter your perception which is enough to make most patients feel comfortable.

Relaxed But Aware: Nitrous oxide removes anxiety and fear, and it relaxes you. It does not make you fall asleep. You'll still be aware of your surroundings, and you'll be able to respond to questions. You just won't be worried or afraid about what's happening. The recovery from nitrous oxide is almost immediate, so when you're done, you'll be right back to normal. It's good stuff, but not all dentists offer it.