I disagree wholeheartedly. I felt the last two episodes were two of the best in the series so far. Both did a much better job of capturing the vibe of the comics. Any good zombie narrative should focus on man vs man - the "zombie apocalypse" just serves as a backdrop to drive home to what extremes mankind will go in such circumstances.
And no... I don't think the zombie scenes were shoe-horned in. I thought they were used effectively to showcase two "enemies" interactions during a cease fire. Darryl and the other guy probably had more in common with each other than they do with others in their own groups. It was a dynamic that was interesting to watch and very poignant when they both acknowleged that eventually they would have to turn their guns on each other in the end.