It IS hard to get into. It has introspective characters hiding secrets not just from each other but from us too, it's quite hard to know what everyone is thinking. It has very odd storyline constructions, characters appear and are interesting and you commit to them, then they are not involved for 5 weeks, while others with no special storyline development are pursued. It's one of the quirks of the series.
I felt the opener last week was strange, it was slow and lacklustre in terms of plot, though the situation and characters remain interesting. It constantly referred to things in the last series, and that was hard to recall as the BBC has held it back for so long - I know they just repeated the first series but I didn't intent to watch 13 hours again.
I hope it is not going to turn self-indulgent and insiderish, I don't like that.