I'm one of those people who admires Frank, let discomfort ensue.

Many surgeons are sociopaths, by the way. "Sociopath" is just the fear-inducing buzzword of the era, like "Communist" or "Punk". Just because you purposefully wield the social conventions that others unconsciously make use of doesn't make you a bad person. Frank's defining flaw isn't his sociopathy - it's his megalomania. He inflicts his emotions (usually anger or irritation) on others and gets offended when they do the same.

Ultimately HoC is a character drama that also, as you said, displays the irreconcilable dichotomy between ruthlessly effective government and meritorious constitutional ideals (highlighted by Frank and Claire, respectively, and their relationship).

That said, it's the audience (and the supporting cast) that forces the show and Frank into that dichotomy. Frank's unscrupulous actions wouldn't be necessary for effective change if everybody was willing to let go of their security blankets (e.g. a sliding scale of "Good/Bad" morality, unwillingness to pursue major reform without public approval, and narcissism). That doesn't exonerate him, but he is forced to either abandon ambition (and thus self-worth) or harm others because the system is otherwise impossible to intentionally navigate, which was the whole point of the initial "no VP for you" debacle.

This isn't just fiction, look at what happened to President Barack Obama: he promised sweeping reforms and then had everything, even his pet project (Obamacare) gutted and mollified. The bill (Affordable Care Act) was eventually passed in 2010 and still, 3 years later, the Republicans were still trying to shut it down by holding the freaking government hostage.

Point is - yes Frank is ruthless but, he's ultimately trying to help millions-billions of people. It's the same moral dilemma as the Hiroshima/Nagasaki bombings. Unfortunately, I think the creators changed their mind in S3, because it really seems like they're now going the "hubris is the fall of man" route and showing how ultimately everything Frank worked for will go up in flames (or, more appropriately, collapse) because he was a dick. We'll just have to wait and see.