I'll be honest, S1 seemed brighter and had more impact, but S2 is excellent in its own right.
The same great wealth of characters, excellent relationships between the main cast friends, lovers, families and the hospital's patients' too, with their individual stories.
As with S1, I didn't feel it got too overly melancholic, or ridiculous. When people grieved it felt real, not over acted.
The ongoing plot lines of S1 were picked up well and concluded, so I can't imagine there'll be a S3. I shall miss them and the weekly band meets. I will definitely watch both again one day.