This is a great series from many points of view, but I will list three. First, there are many sub plots which supports the over all story line and keeps you engaged. Then there is the cast and their acting depth and capability. And finally, there is my favorite, the plot. I believe the story is within the story. Love is central, but adding the struggles of emotions from a human and artificial intelligence perspective creates a cocktail that is both satisfying and enjoyable to watch.