I really like this show, it's formula is not overly predictable. The characters are well developed and likable and well missed when absent. You can completely invest in the stories as they unfold.
The time period portrayed feels real, it is captured both through a more innocent time, but with a realism that shows that even in a gentler time there is more to the world than tea and crumpets.
Whenever something wonderful happened for the main characters I found myself smiling or laughing, clapping my hands with joy. And when something terrible happened I was angry on their behalf or crying with their friends and family.
The realism and therefore terms or language used that in the present day would smack of prejudice or more likely ignorance, tho shocking were necessary and integral to the story being told.
And watching the progession of medical discoveries; clothes, hairstyles and social norms evolve was a little bit of history told thru the eyes of well loved characters.
Seeing that people are more or less the same, only times change, but humanity remains is reaffirming.