First of all, watch it in its original Spanish, w subtitles if need be. Jose Coronado and Luis Zahera (especially Zahera) and a few others really carry the series. The Irene/Nelson love story is punishingly sappy. Any scene with those two really drags. Pretty bad acting from them..
Just like Vivir Sin Permiso (Unauthorized Living) the show schizophrenically switches between exciting crime intrigue and awful soap opera. Also, just like Vivir Sin Permiso, the only reason I really stick with it is for Zahera and Coronado, two of Spain’s finest actors.