Does DEA Agent Murphy still narrate in an annoying manner?
Not as much! Although I enjoy learning things, Agent Murphy's dual role as narrator and major character in the first season caused the show to over-explain things it could have just had us watch go down. Perhaps they did this because 75% of the show is in Spanish (which is absolutely the correct way to do it -- I've always disliked movies that, say, were about Russia during the Cold War, but the characters spoke to each other in Russian-accented English), and they felt like an English-speaking audience would miss their native tongue if Murphy didn't jump in and tell you the facts.
In Season 2, Murphy's narrations are cut down by 60%. His narration is even playfully interrupted in one of the final scenes, when he starts to get philosophical. Part of this is likely situational -- the first season covered many more years documenting Escobar's rise, while the second season only has one year to play with. Regardless, it is appreciated.
What are the best parts?
Generally speaking, the eight episodes directed by both Colombian Andrés Baiz and Josef Wladyka (who spent years in a terribly dangerous part of Colombia to make the independent film Manos Sucias) are markedly improved over the first two from Gerardo Naranjo.
Specifically, there is one scene in which Pablo's sicario "Blackie" has been dispatched to the hotel where his wife and children are being kept under government supervision. Blackie clearly can't see them, but he recognizes that his boss is gingerly walking on thin crazy-person ice, so he pretends he has spotted them, closing his eyes and describing their outfits and demeanors to Escobar. It is a weirdly caring and emotional scene between two people who have played a major part in destroying a country.
Also, a few scenes in which a random family is shown having breakfast as one of Pablo's bombs goes off nearby, and again in a pharmacy after another bomb is planted. These segments follow that Six Feet Under style of suspense, in which you know something bad is going to happen to these innocent people but you're never exactly sure when.
Oh, and Pablo Escobar's outfits, which look like they were picked out by an '80s father of three managing an animal shelter in the cool section of a Midwestern town, are worth the price of admission. They're like Macklemore's ironic thrift shop wet dream.