I loved the series finale of Breaking Bad. There were many great moments, but the one that really hit me was a quick flashback to the first episode of the series. Hank is goading Walt into coming on a ride along with him on one of his drug busts. I don't remember the exact words, but Hank says something about Walt doing something exciting for the first time in his life. Walt shyly says maybe he will. We get to remember that at the beginning of the series, Walt was dismissed by everyone as a loser. Setting aside the Gray Matters storyline, the series casts Walt as the mild-mannered shulb who discovers he has a secret power and he uses that power to show the world he's not a loser.
This storyline is the same as most of the early comic book superheroes, in particular Spider-Man who is also a meek chemistry genius who hides the fact that he's a superhero. This is the wish fulfillment fantasy of all geeks who were bullied by jocks and ignored by cheerleaders. And the same fantasy of all of us who feel the world is screwing us over. We wish we had some power that would help us to rise above our shortcomings. How many of us don't wish we could say, "See world, I'm a badass and I'm not taking your shit anymore." That part of us that feels marginalized is the part that rooted for Walt.
To the show's credit, instead of being like Spider-Man and using his power for good, Walt became a supervillain. Look into the origin stories of supervillains and you'll see that the only difference from the heroes' beginning was their moral choice of how to use their power. That moral compromise is what made Breaking Bad a much more interesting story.