So far, I've enjoyed Season 4. There have been some truly surprising moments, like Sayid working for Ben in the future, and some nice character shows (such as the Desmond-centered one and the Sun-centered one.
The last few episodes weren't as strong, I think because they went back to the old LOST style: noodle around in the episode, have flashbacks (or flashforwards) that are more tricks than information, and then have something big happen off-camera and don't show the audience what it was. But overall, it's been a solid season that is making some real movement forward. I'm definitely looking forward to the rest of the season.
What I think was needed in "Meet Kevin Johnson" (last episode, Michael-centered) was a scene with Michael and Walt where Walt disowned Michael because of what Michael did. This would have started Michael down the self-destruction path. However, the actor playing Walt has changed so much in the three years they couldn't have that scene. That's life in television.
Having Ben be a controlling possessive crazy guy (in the Juliet-centered episode) is something I was 50-50 on. On one hand, I liked manipulative Ben whose only goal was saving the island rather than just "owning" Juliet. On the other hand, it did make Ben a little more human.
I still think that, in the future scenes, Jin is alive and Claire is alive and that the "Oceanic Six get off the island" is going to be chaotic, confused and messy. Interesting point: When Abbadon asked Hurley "do you think they're still alive?", maybe he was referring not to the Losties but to his crew.