S1 started slowly but got me all riveted when it got going by Ep 3. I think that there were too many twists and turns at the end but that is to be expected when the crime is of a "historical" nature, all those culpable or related within the 6 degrees of separation, move on with their lives when it's an old and cold case. My opinion is that the great and top notch acting carried the day when it came to the conclusion of S1.
I'm still looking forward to watching S2 but now that I think I've figured out the M.O of the show, it remains to be seen if I can figure out the whodunnit