Well, the series has running time close to 17 hrs, which means every character on the show gets sufficient time for character development, revealing themselves layers by layers. The show never loses its pace keeping you on the edge with its twists. On top of that, add a rebellious track to it (Bella ciao) and the cocktail will give you hangover for days even after finishing the series.
There are some loose ends to the series which are a bit hard to justify but it doesn't stop you from enjoying this brilliantly crafted series. I saw the English dubbed version while the series is originally in Spanish. I enjoyed it but Spanish version might be more authentic.