Well it's a political drama shown primarily through the perspective of a cold, cunning, and hilariously weary Majority Whip, so it throws a really nice twist on everything and works brilliantly for television... the characters are really what drives it.
It's such a cutthroat and cloak & dagger presentation of Washington's elite, and that provides something endlessly watchable. I'm loving it, and if any of what I just mentioned appeals to you, the feeling will be mutual.