Just binged the first season (& haven't read the books), so some thoughts....
The only person I felt absolutely no pity for was Wilson [the rapist turned serial killer]. If given the backstories for the rest of the 'death row virals' maybe I'd've found others, but Wilson was the only one with no redeeming qualities or a hinted-at horrible past to be pitiable. If Lear or Richards had been offed, I wouldn't have blinked an eye. The only slightly redeeming thing about Lear was his love for his wife, everything happened because of his selfishness to not put the needs of the many before the needs of the few, or the one. Which, ironically, starts the whole thing because he didn't put the needs of the one (his ailing wife) before going to Bolivia, which kick-started everything.
Despite them being murderous blood-lusting vampiric 'virals', I really felt sympathy for Carter and Babcock. I realize, what with their telepathic abilities, they could have been putting on acts to convince their "victims", but it didn't feel that way to me. I really felt that despite their true appearances and base functions, they didn't want to be that. I was no Richards fan, but that flashback of him chasing Babcock down and then going to that diner, when she begs him to run with her, it was slightly heartbreaking because he seemed to truly want to do that for her, but then he remembers she's already been 'infected' and there's nothing he could do. Although, I have to admit being a bit icked out by the glaringly obvious parallels between Babcock's 'relationship' with her step-father and her seducing Richards, especially in the age difference.
As much as I really dislike young children being a main focus on shows I'm watching, Amy was a real treat. Her and Brad were amazing together. I'd like to think that every father would wish to have as good a relationship with their daughter as Brad had with Amy (& they were complete strangers to start with, and he was [one of] her kidnapper(s)). Can't give that integral part of the show high enough marks.
The government conspiracy of killing the reporter and attempting to kill Brad & Lila was a bit much, but helped keep the stakes high.
Not having knowledge of the books probably hampers me (no spoilers please), but the "power of 12" thing never really made sense to me. What was the significance of Fanning needing/having 12 virals in 'his family'?
The 80-year time jump should be interesting if they get a 2nd season [which I am in for, if happens]. I'm gonna guess that the cure still makes people 'immortal' - or at least severely slows the aging process - only without the vampiric need to feed or weakness to high-powered light. I mean, Brad isn't going to be alive 80 years later if not. Which also means, very good chance Lila will still be around as well. Putting money that Lear either did make a 'cure' as well, or it changed him in other ways and he'll still be around.
Again, with no knowledge of the book, the attempted killing of all the virals in E5 - but aborted because of Amy's & Elizabeth's connection - felt like a massive plot hole. I understand the plotline of having the sire's death meaning death of all his 'offspring', but then how & why would Fanning survive his turning if his sire was killed just seconds after infecting him. It doesn't compute in my mind. But, the rest of the show was good enough to overlook it. Could have used an (at least) off-hand comment about why it was happening then and not with Fanning in Bolivia. I can somewhat buy that considering how soon the sire was killed, that Fanning's infection didn't have chance to take root, but if that's how, then explain that. Without an explanation, it looks like really bad writing and/or retcon.