The novel on which this series is based is sophisticated and the plot is complex. It is original and mature writing (it won the prestigious Man Booker Prize) but it's definitely not easy reading.
Given this, it's asking too much to expect mere entertainment from a TV adaptation. The story is too complex to be reduced to the level of simplicity that many people want and expect. The novel demands active involvement for it to be rewarding; the TV version likewise.
It's near-impossible to reduce a nearly 1,000 page novel to six hours of television. If this sounds like justification for the TV version's complexity, that's exactly what I'm trying to do.
It's certainly isn't easy going, but it is rewarding if you're prepared to provide input yourself - just like the novel.