I didn't watched the series (but i'll probably do sometime in the future - i mean, it's procedural and all) but I liked the episode. it had some pace, a few surprises, and all in all it would have been decent even without JB.
btw, i liked his look here. it was like a little rebellious behind the middle class. (idk if that makes any kind of sense) and i liked his performance. it wasn't his best but it was solid and played transmitted all that i think that they expected him to.