This one is definitely one of the better Spanish and crime series for me, because of the acting, the script (distilled from a good novel) and the whole atmosphere created by the director(s). I was also pleased to see that they didn't put on a "bad wig show" in the scenes that took place in 2010 (the kidnapping of Amalya), and 6 years earlier.
I haven't seen season 2 yet, but I definitely will. Season 1 reminded me of the British "Missing".