Punchline is located on the second floor, so you have to take a flight of stairs/elevator up. At the door they check your ID, and then take you to your seats. I was relieved that I didn't end up sitting in the front, within the comedian's line of sight. I didn't want to be a target of their jokes. Comedians are  hit or miss depending on the night you go. Both times that I went, there were two opening acts before the main act.
What you need to know is that there is a two drink minimum. When I first went there, I found it a bit odd but I guess that's how they make money, especially when people can get in for free.