The enormous swarm of walkers was well worth having, tension wise, but the 'explanation' offered at the beginning of the episode for their getting to the farm was pretty far-fetched. A handful of walkers spy a helicopter going past and so they all start migrating towards the farm.
I'm unsure how Maggie and Glenn managed to make it out alive. I'm glad they did, don't get me wrong, but they stopped in the middle of a huge crowd of walkers for a good long time, yet the walkers weren't able to get through the windscreen or even surround the car. Given that one walker got through Lori's windscreen a few episodes back in a relatively short time, you'd have though that twenty plus walkers would have been able to do it. Likewise, it was a bit unbelievable that none of them were behind the car.
At the beginning of the episode, there seemed to be the potential for any of the characters to be killed off. In the end, they went with the safe 'kill off the excess characters', the two characters that have had little or no relevance to anything. It seemed like killing off characters for the sake of having some deaths to ratchet up the tension. The way they were killed seemed like they wanted it to happen. I forget both their names now, but the guy who drove the RV to help Rick and Carl off the roof seemed a preposterous death. He could've let them onto the roof, made sure they were going down onto the car/jumping off and driven off. Instead, he abandoned the wheel and went for a slow motion stroll through the RV, before being killed in an almost Shaun of the Dead's David style of death (pulled through the doors while doing absolutely nothing to prevent it). It seemed that he hadn't even bothered to lock or in any way secure the door. The woman was picked off a bit at random from the group of three, and realistically Hershel's youngest daughter wouldn't have made it out of there either.
The final negative point was the ease of the group's reunion. I wanted the central characters (i.e. the group from Series One, as it is now, and Maggie/Hershel, kind of Hershel's other daughter) to make it and be reunited, but it all felt a bit easy
. Daryl and Carol's ride past the walkers was a bit like a ghost train, where they lunged out of the sides of the road yet were totally unable to move forward or in any way react or pose a real threat, despite the incredibly slow pace of the bike. Likewise, one minute it was 'will we ever find them?' and tension/drama, and in the next, literally every
one of the cars, with everyone except Andrea, appeared. Good not to let it drag on, but they could've at least made the reunion a little more tense/harder.
The character with the hood - who's apparently a woman - had two armless zombies on chains. They seemed a bit gimpy, and the whole scene seemed a bit odd in general. Very convenient too (though most near-death rescues are in The Walking Dead tbf).
Genuinely wasn't expecting Rick knowing that everyone is infected to be the case, but it did tie the story together nicely. Lori's reaction seemed to be more to do with the way that Rick was sounding like Shane in his callous 'he was always dragging on me' monologue. Not sure why he didn't make more of a thing of the gun pointed at his head at that stage.