Common Sense Note
Parents need to know that Breaking Bad isn't intended for kids; its intense, morally ambiguous characters and storylines are a much better fit for mature audiences. The main character starts out as an essentially good person who's driven to extreme negative behavior (manufacturing methamphetamines and more) by depression and desperation; over the course of the show, his good side becomes less and less evident. There's a good bit of swearing (though "f--k" is muted on the network airing, but not on the DVD or streaming versions), frequent violence (sometimes extremely graphic), and some sexual content (a woman is shown topless, but her breasts are blurred on the network version, though not on the DVD or streaming versions).
In one scene, a bare-breasted woman leans out a window, but her breasts are blurred out on the network version, but not on the DVD or streaming versions. Walt and his wife have some intense sexual encounters, but nothing graphic is shown -- it's all implied.
Frequent graphic violence. Shooting and threats of shooting; other physical scuffles, beatings, and attacks; explosions (some with horrifying results); poisonings; accidental deaths. In one first-season episode, in an attempt to defend himself, Walt creates phosphine gas and poisons his attackers; later, the consequences are shown, and Walt and Jesse must dispose of one of the bodies -- which turns into a disgusting, bloody mess.
Audible language includes words like "ass" and "bitch," while "f--k" and "bulls--t" are muted on the network version, but not on the DVD or streaming versions. References to male anatomy, including "dick" and "prick." A character flips some others the bird.
Although Walt's actions are (at least initially) motivated by his desire to provide for his family, the show's take-aways are pretty grim overall. Good and evil are constantly muddled, bad things happen to "good" people for no reason, many characters do horrible things in the name of revenge, and there's no reward for doing the right thing.
Drugs / Tobacco /
The show revolves around making and selling illegal drugs; some characters are addicts. Walt is touted by the dealers as an artist for his skill at making methamphetamines. Also drinking and prescription drug use.