Ok, a few negatives first.
1. The number of headshots, while driving and bouncing and turning, just ridiculous.
2. Rick's wife suddenly mad at him, even though she basically told him Shane had to be killed.
3. Why did they have to leave the farm? Why not draw all the zombies out. They are attracted to noise, go out a ways, make a lot of noise to attact them. Lead them out for awhile, even hours. Drive off in the direction that leads them away (heck they clearly showed this group walking all the way from Atlanta to follow a helicopter so clearly the zombies would continue in that direction for days, months). Then do a big circle/loop and come back to the farm when you are out of sight/sound from the zombies, problem solved.
4. Why are they mad Rick is now telling him about the CDC guy??? What would you of done different knowing that info earlier? Just dumb writting on that part.
Other then that, this was hands down the best episode of the series. Amazing opening scene. Loved how they answered all the questions on the fence and how they could of gotten in. Intense fight, on the edge of your seat kind of stuff. Love how Herschel is backing Rick so solidly. Darryl finally back to being Rick's go to guy, that just fits sooo well. Love Michone's introduction, loved the prison scene. Just sooo many good things, wow, amazing episode.