I am still greatly enjoying homeland, but the nonstop pace of S1 could only have continued if they had decided Brody could die. The minute they decided not to blow up the bunker, I think it was no longer possible.
The first season's writing struck me as if it was inspired by Breaking Bad. They approached Brody similarly to Walt, where both characters were seemingly good men who were motivated to do horrible things. Brody and Walt often engage in behavior you normally wouldn't expect from a protagonist. The difference is Homeland exists in a larger world where Brody's actions have much further reaching implications, due to the show involving the federal government and its foreign policies.
Because of this, Brody's actions should be met with much larger consequences, something the writers appear to be very reluctant to do. Instead of him being thrown in prison with a death sentence hanging over his head when its found out he's been working with terrorists and almost took out the government with a suicide vest, we get him hanging out with the vice president with barely any supervision. The show seems desperate to want to keep reminding us that, despite the things he's done, Brody is just a good guy in a bad situation, and the good guy always lives to fight another day. Which is why I think he ceased to be such an interesting character: He's become more typical - a good man trying to clear his good name.
Though, I have to say, one of the things I am enjoying about these season so far is that they actually do appear to be dealing with some of the ridiculousness from last season. The congressional inquiry seems to be designed to address some of the criticism they got for last season. Unfortunately, I'm doubting that results in any real consequences for the main characters, because, let's face it, that would involve Saul being fired or scapegoated for how incompetently Brody was handled and Carrie, at best, being demoted to a desk job, if not being thrown in jail for aiding a terrorist, and there wouldn't be much of a show then.