Enrico Colantoni is a terrific actor and fellow Canadian. :) I love him on Flashpoint and recall seeing him on Bones, where he did a lovely job with the night watchman role as he interacted with Dr. Brennan. This role was quite different and very, very well played.
I think this was the best episode of the series so far. I like it that Det. Carter has a more prominent role because the show needs a female presence otherwise it gets too close to being a shoot-em-up Chuck Norris type movie, and I don't like those at all.
I'll avoid spoilers, so let's just say that the ending was the best of the series and when Finch and Reese spoke about the work that they do, the outcome here left them wondering about it. It definitely but a shade of gray into the mix that wasn't there before. Terrific episode all around.