Gotta say, Season 5 opened quite well. The reincorporation of rational thought was a nice addition. From S2E1 beyond, I have to use the headcanon that almost none of them had passed elementary school because there are some things they do that are just unreasonably stupid and because they pretty much never used anything they learned ever again. I mean fucking medieval people had more sense than them. Hey, Rick, dig a fucking moat around the prison. That'll stop the walkers, as evidenced by Woodbury's success with them, and it would've stopped the fucking tank from rolling into the prison yard. Everything of significance in the first half of Season 4 (except maybe Lizzie) could've been easily prevented by putting on a 24-hour watch and digging a big fucking hole around the prison while you had people guard those digging. Granted, its good to see that the carryover from Season 2 of ignoring everything that they had previously learned[1] is likely to be missing from Season 5. Finally. Granted, it wasn't that bad in Season 3, except for maybe them being absolute idiots and not clearing out the prison at a safe pace.
Also, Carol kicked ass, holy shit. Make her the leader of the group already.