In my opinion, the best season so far. I thought the infection in the first half of the season was very interesting with Hershel caring for them and risking his life for them. The three episodes focusing on The Governor were excellently done, and I think episode 8, Too Far Gone, is the greatest episode of the whole show. Non-stop action and suspense.
The second half of this season was also superb. I loved the idea of Terminus, and seeing it as a sanctuary for all. The second half mainly focuses on character development and smaller characters, such as Tyreese, Beth, Abraham, Eugene, Bob and Sasha. Helps us understand the characters more and bring them into the story more.
I think the season finale was excellent, with the focus on Rick, Michonne and Carl. The main antagonist of the second half of the season, Joe and his group, are seen hunting for Rick, and succeed. I loved them bringing the old Rick Grimes back facing sheer brutality and being pushed to his absolute limit. The ending was exceptional, with the final line by Rick Grimes saying 'they're screwing with the wrong people'.
My favourite season thus far, cannot wait to see what season 5 has in store, and would recommend this season to anybody.