A strange man approaches you and offers you a briefcase. You've been gravely wronged in the past, and the briefcase contains absolute proof of who wronged you, a gun, and 100 untraceable bullets. What do you do?
And that's the main point of 100 Bullets, putting a series of characters into that situation and giving them the choice. And being flawed people who are dealing with a dramatic revelation, they make flawed choices. Azzarello was good at that, making these people and their decisions believable. And since the storylines are short overall (2 or 3 issues each, in this trade) you won't be stuck with a story if you can't get into it. I do understand that the series eventually moves away from the anthology feel to an overarching storyline, and there are hints of it here. I'm interested to see where this is going.
The art is filled with dark, dramatic shadows, which suits the story. It's not something I normally like much, but it makes sense here.