Working with friends sounds like a dream: you have someone to bitch about your boss with, you have the same schedules (meaning the same free time for happy hours), and — most importantly —
you have someone to sit with at lunch.
With the good times come the bad, of course, and you might find yourself in a situation where your friend isn't putting in the work, your friend is making you look bad by association, or your friend is making you be the bad guy. Here's a textual situation I received from someone who hired her friend at the company she works at: