There's have been many docu-series covering the history of ETA over the years but this one sets out to be the definitive one, unlike previous attempts this one covers the whole history of ETA in great detail, and its full of interviews with almost all political actors, not to mention plenty of testimonies from victims and their families.
However I don't necessary recommend starting with this show because it doesn't introduce the personalities that inhabit the story, you are supposed to be already familiar with who the presidents where, who Franco is, who the PSOE and PP are, and what is Batasuna, the atrocities itself are presented as if you are already familiar with them at least by name, and they are introduced pretty quickly. Nevertheless the story is told in great detail and the creators have made sure to cover almost every single terrorist attack.
The testimonies from the victims are harrowing and admirable in how eloquent they are and they *will* make you cry. If as if their suffering have given them an almost panoramic view of the whole conflict, without hesitation they go deep into the heart of the matter.
Besides that, the only real criticism I have is that documentary makes too many excuses for the state terrorism that the Spanish state deployed to combat the terrorism of ETA, too many interventions by military and police justifying or minimizing the violence and too little time spend talking about GAL.
Also while the show interviews people from Batasuna, the political wing of ETA, it doesn't actually interview a single member of ETA, im sure someone like Josu Ternera would be willing to give their version of events and it would be interesting to see what they have to say in their defense, if only to show the impossibility of defending the magnitude of ETA terrorism.
Overall, this series success as the definitive retelling of this story thanks to it's extensive coverage and high production values, from now on it is probably going to serve as the go-to documentary on the subject.