I have been an obsessive of this series for years. I can't deny that I have found this one more difficult to love because the actors from series 1, 2 & 3 felt like friends and they were SO good in their roles. They perfectly embodied the characters, especially Lenu, Lila, Michele, Stefano, Pinuccia, Marcello and Enzo. The fact that the older actors playing Nunzia, Immacolata etc were all the same actors as before made it all much more jarring. I know there were a lot of people arguing that the younger actors could have not played their older characters but I'm not so sure. The change of actors meant that the huge cast were often lost as I sat there going "who is THAT?." And some choices were.... very odd. Antonio looked like he was pushing seventy, even if he'd had a hard life. I found the new Solaras just wrong: they absolutely did not have the same menace and brooding of the younger actors. On the other hand, the new Nino and Lila were great.
In all, I really enjoyed it - for what is a very harrowing watch, especially the further in it gets. It is certainly one of the few series which forensically examines female friendship, motherhood (and the mixed emotions/expectations this brings), class movement, impact of poverty etc. It is a huge accomplishment for the cast and crew and I do hope they scoop up some awards so that more people become aware of its brilliance.