2. The Emotional Resonance
Its just so human. Though they are excellent, you just dont give a damn about the production values, the attention to detail on the sets, the props, the lighting or the costume design. You care about the love triangle and what happens to them, and how they feel. The feelings are universal and conveyed on the level of us mere mortals- we arent looking in from the outside, we are standing right next to the characters as they experience joy, misery, love and loss. Even the starched, uppity, pompous Tietjens is relatable. And it can sometimes be quite funny, without ever feeling forced, and without ever playing on class differences (in fact, you rarely see working class (hate that term) people, which plays to its advantage- we focus on a sector of society, and not there reactions to other sectors). It is closer to a good, intimate drama with characters we care about, like
This is England, than it is to unrelatable tripe like
Larkrise to bloody
Candleford.