What's very interesting is just how close this is to how he's portrayed in both "Uncanny X-Force" and "Thunderbolts"; sure, he's insane, but he's shown that he's a good man who, truthfully, just wants to do the right thing.
Stinkoman87 just wants to add something: he's funny, but in a raunchy way, and uses guns. Deadpool is what would happen if someone made Spider Man in the modern age.
He also strikes a good balance between "Ax Crazy murdering sociopath" and "Guy who honestly wants to do the right thing but keeps getting the Heel Face Door Slam". Just bloody enough to be badass, just annoying enough to be hilarious, and just messed up enough to be sympathetic.