The teams at Overkill and Dennation Games even provided a short FAQ to give you a bit of an idea on what to expect in this DLC.
A: This Hotline Miami DLC for PAYDAY 2 is a true collaboration between OVERKILL, creators of PAYDAY and Dennaton Games, creators of Hotline Miami.
A: Because we at OVERKILL fucking love Hotline Miami.
Q: Never heard of Hotline Miami.
A: Buy Hotline Miami and support our friends at Dennaton Games.
Q: When is DLC this released?
A: September 30th!
Q: What does the DLC contain?
A: A heist is confirmed - you'll find out about the rest come end of September.
I mean, they're not wrong here. Hotline Miami is a fantastic game with one of the best game soundtracks you'll ever hear.