The acting isn't what's the problem, some of the writing is just weak around a few characters. The acting from those behind Daryll, Andrea, Rick, Glen, Maggie, and Hershel is great, my biggest complaint being the inconsistency of the writing behind them week by week.
Can't wait to see how the addition of Michonne, Tyresse, the Gov, and the possible return of Merl affects the group.
I have to say I was shocked recently when I learned that one of the differences between comic and show is that the Dixon brothers (Daryll and Merl) don't appear in the comic. I bet the writing behind them gets a chance to grow their characters in the prison.
And how racist would it be if T-dogg - the one black guy, after getting no lines all season, finally gets some screen time - in the prison season?