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.
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.
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.
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.
Drinking, Drugs & Smoking
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.