When the show started, tagging it as "Science Fiction" was ... peripheral. Our heroes were tracking down people whose Social Security Numbers they received and trying to prevent their deaths (or prevent them from killing others). They got the numbers from "The Machine," but it didn't feature heavily. How they get the numbers is now front and centre, and it's all about The Machine and the whole season features the attempt by the very shadowy "Decima Technologies" to create their own more dangerous version of it, "Samaritan."
The show is certainly suggesting relevant questions about surveillance society and AI - whether or not anyone is paying any attention to the questions asked in the age of Donald Trump is unclear. Okay, it was filmed during the Obama administration, but I'm watching it now and Trump's rise only makes the questions more valid.
I like a lot of things about the show: the cast is dynamic, but the new people are often introduced months before they become a major character. The writers are thinking ahead and doing good planning, which pays off for us. I'm not enjoying the turn to pure paranoia, with them being the hunted - they've always been hunted, but by the beginning of the fourth season it's become a dominant factor. The high school reunion episode was hysterically funny (episode 19 ... although its central mystery wasn't terribly exciting), with a pair of trained killers (Reese and Shaw) trying to fit in among accountants and mechanics.
Overall, a good season.