This is where many of NYC's finest stuntmen and stuntwomen train, and celebrity trickers and bboys tend to show up from time to time.
First-time visitors are usually asked to take a class before hitting open gym. And with great instructors like OG tricker Manny Brown, it's not the end of the world. But if you already have a lot of experience and don't wanna bother with a class, just be ready to show video evidence of your skills when you sign in for your first open gym. You should be fine!
Lastly, think about sneaking up to the roof by first taking the elevator to the top floor. Don't get caught, especially before the staff knows you, but you get a great view of the city from up there.