Hola,
As mentioned in some of the posts, and living in the Mayan area (Playa del Carmen)... life is as dangerous as you want it to be. If going off resort and hanging out in bad parts of town... you are bound to find trouble. If looking for illegal activities, as with anywhere in the world, your chances of finding trouble are going to rise.
If you sticking with "main stream" tourist activities... in "main stream" Mexico.... you will be as safe as you are anywhere in the world. There are thousands of people around, including police and military (that's just the way it is here), that want nothing from you but to make sure everything is safe for everyone.
I feel safer here in Paya and going out at night than I would walking downtown in my home town of Calgary Canada.
Im sure the media will continue to "sensationalize" stories in Mexico. The fact remains... if you want to pick a location, any location, you can talk about the horror that happen there. I bet Mexico is a lot more safe (especially in the Mayan area), than it is where you live.
That is just my opinion... but I am bias... I live here and LOVE IT!
Lincoln (& Lori)