For starters, how the heck did a horde of zombies get to them that close without anyone of them them noticing earlier? Wasn't Dale on the roof of the RV for a while before the walkers arrived? Although I liked the the action and that entire sequence seemed enjoyably tense.
I found it a bit odd though that Rick opted to leave Sophia in the woods when he had other better and more obvious options imo. That was either poor writing or simply a major ****-up by Rick. Either way, I just didn't like how it led to the rest of the episode being them just looking for the girl with little advancement in plot. Some character development was nice, but for a season premiere, a huge chunk of it felt like I was watching a filler episode...
The one character that I thought was great in the episode was Lori. She seemed like she grew some balls since last season. She seemed genuinely toughened and put people in their place.