I've been playing Blades in the Dark for about a year and recently I started my first game as a GM. The heist deck is a great source since it offers a lot of ideas that fit really well into Doskvol and therefore it makes being a GM much easier.
I especially like that there is an additional document that tells you how to adjust the obstacles (make them more or less difficult).
I recommend buying these PDFs and printing the cards yourself - they perfectly fit in standard card sleeves, so you can actually use it like a normal deck (especially if you use sleeves with different colors).
[5 of 5 Stars!]