I work graveyard so I am a night person by default - virtually nocturnal actually, I don't see the daylight very much.
As far as the pros and cons - there's free parking downtown at night. The few calls I get are usually more interesting than daylights. I'm home and awake in the evenings to spend time with my kids when they get home from school.
Biggest con would be trying to sleep during the day - the light, the noise, people mowing their lawn when you're trying to go to sleep, etc.