I'll admit that it wasn't entirely because of the case. I was glad to see Fin get an episode mostly centered on him and his family. Actually having a bit of a Christmas theme with the opening and ending was a nice touch. We got to see the characters happy and more relaxed than in most episodes. There was plenty of sass and comic relief but they knew when to get serious.
The ending I thought was nicely done, we were distracted with a pleasant scene with Amanda being invited to stay and have dinner with Fin's family. (Which I LOVED but at the same time I hope they touch on the fact that Ken is and was not invited again to a family get And the last couple of seconds, the victim ruins Amaro's attempts to arrest the actual perp.
I'm not even going to comment on the hand other than saying... I know some people were going to try and compare hands from previous seasons etc to find a match. I'm pretty sure Pino was in that scene just to shoot it, however.... It's obviously not Amaro.