We get to see Carter as the realistically tough cop, doing her bit to make the world a safer place with little regard to her own safety, and find out more about her personal and past life. In itself this makes for interesting viewing.
Tie in several plots (so the latest threat is hard to uncover) and bring in the Elias story arc (which is always curious because it is so underplayed in many ways), and then add Reese being a tough-ass.
And when he gets his tough-ass on he's a treat to watch because it looks like it's real and very natural for him to wander about with a grenade launcher and string up violent offenders with power cords. Again, he does it in such an understated, almost mundane way that doesn't glorify violence - it's just done and dusted quick and over, then back to the story. And that makes him so much more believable.
His grudging admiration for Carter was always there but now he's protected her he's even more a fan, and in any other series I'd suspect a lead up to a romantic interest or the will-they-won't-they thing, but in this show I don't expect the obvious.
Nice to see the character of Fusco getting more time and seeming to choose sides, and it's always a pleasure to see Finch out there doing his thing, even if that includes rummaging around in a car.
Still so many places for this show to go and explore. Looking forward to following further - and so glad it hasn't just stopped for Christmas hiatus crap like all the other shows I watch. If nothing else it deserves an honourable mention for not letting me get bored over November/December.