One of my favorite parts about this season has been the lack of Jack. It's probably because the story is in so many places now with so many people, as well as Jack generally taking a backseat this season, but I was kind of getting sick of him rallying the troops and running the show in the first few seasons. Glad there is a new Jack.
Also, Lost does a great job of killing off people I don't like quickly, and then building up the deaths of people I do like. Ana Lucia, Libby, Frogurt, Arntz, Caesar, Boone, and Shannon, Naomi, for one reason or another I'm glad they're all dead. Charlie, Faraday, Mr. Eko, possibly Juliette

. There's more but I feel like I've listed enough.