Finally got around to watching the second half of season 2 (Episode 7-13) and it was A LOT better than the first half
Shane slipping into insanity was masterfully done. Carl losing his innocence, Glenn/Maggie, Daryl evolving (And becoming a more capable leader than Rick in many ways, yet he doesn't step up) and Rick stepping up like a boss at then end were all highlights for me
A few things I didn't like as much though: Lori going full hate on Rick when he reveals he killed Shane, makes no sense. A few episodes back she told Rick that Shane was dangerous and that he should be killed - come on, the writing staff can do better than that.
Dale dying sucked as well, I really liked him and he was really awesome as the groups "link to humanity" in a world where humanity is scarce.
That being said, still an awesome show and two awesome seasons down - can't wait for the third!
Especially now that they're heading to the prison and we've been introduced to Michonne (Who is just a bad ass)
Also - next season another big character from the comics will come into play, won't spoil it but it will be awesome!