Just finished the first season, 7 episodes long. Each episode is ~48 minutes long and there's a good amount of plot development in every single one.
I know pretty much every commentary made by anyone on this series has made note of this but Bryan Cranston makes this show what it is. Having watched him on Malcolm in the Middle, this role really shows off his acting abilities. As Hal, he was such a bumbling fool. Walter White: polar opposite. The guy becomes such a bad-ass.
At the outset of the show he's a pretty soft, almost wimpy, guy. A brilliant chemist who turned down professorships in universities and high-level positions in the private sector, Walt lives his life as an under-appreciated high school chemistry teacher.
This benign lifestyle changes when his doctor diagnoses him with terminal lung cancer. He has a son with special needs and an expectant wife. Furthermore, their insurance doesn't cover treatment.
Walt ends up deciding to 'break bad' and use his chemistry skills to cook high quality crystal meth in order to leave enough money for his family to go on comfortably after his death. At heart Walt is a family man, and the excellence of this show's premise stems from the transformation his dark path has on him as he falls further and further into the drug trade underworld.