The only thing is that you have to realize that it's not a medical drama, like House. It's more of a soap opera set in a hospital, only without the bad writing and acting and whatever that permeates the actual genre of soap operas.
When I started watching it, they introduced the main character (in as much as an ensemble cast has one), and the guy she slept with who was a bit of a sleazebag. But over the course of half a season, things change a bit and you grow to like him. Then his estranged wife shows up, and of course you hate her. But then you come to see that she screwed up, and you feel bad for her. Then the guy she cheated on her husband with drops by, and of course nobody likes him. But eventually you start to realize that, while he is an ass, you really can't blame him for it either; he makes up with the husband, and they go back to being friends like they were before, and so everything's okay.
They've repeated this cycle like a dozen times: introduce a character, get you to hate them, and then transform them to where you actually sympathize with the character enough to like them. Even the characters I loathed from the get-go, absolutely bitterly despised, have been turned around through this process.
Somewhere around the sixth time they pulled this stunt, I started to realize how masterful it is to repeat the same sequence so many times, without it feeling like the show is just recycling the same idea, and to do it successfully every time.
The other thing is that the show is packed with drama. In one episode, it's not just that (say) someone's sister shows up. It's that someone's sister shows up, and someone's fiancé dies, and a couple breaks up, all while victims of a car accident go in and out of surgery, living or dying seemingly at random, to provide a changing backdrop for the on-going drama.