Deserves a high score because it's better than MANY of today's popular shows, just because character and plot development have been relatively engaging and consistent. I remember watching the first ever episode maybe 3/4 times before actually finishing it, and when I did, I watched another. And another.
The introduction of Ava is definitely what gets you hooked initially. Famke Janssen played an amazing villain. Acting is good. Both doctors are believable and Matt is played very well. Vanessa Redgrave as Erica also deserves an award. The biggest problem I had when I started watching this show was Julia. In the first season her scenes were painful to watch, especially when she had them emotional outbursts. She Has improved, but she's still arguably the worst actor of the lot. It's hard to care for her character at all. Even when she got shot, I was more interested in Eden.
The period where they developed The Carver arc were especially entertaining. The organ harvesting storyline was pretty good, but fell in the shadow of The Carver. And after that, the show didn't do much for me. Moving to California took a part of the show away to be honest. Without a gripping plot, it's become yet another TV show about doctors and their messed up lives. It's good that they've decided to quit while ahead, unlike many other shows.
Still, job well done overall