I was a fan of this season, but it wasn't close to the quality of season 1 (not that many shows/seasons are as strong as season 1). I really tried to keep the comparisons from cropping up, but it was hard not to. I thought the acting of Farrell, McAdams & Vaughn was all pretty solid. Kitsch could be good, but other times was painful. I just felt all the diversions from the actual case/story were unnecessary. Some people talked about how season 1's killer felt "unimportant" to the story, but I felt he was far more important and it was far more satisfying to watch him get his than anything with Caspere's killer was in this season. Birdman was far less important to what happened this season. It just tried to have a lot going on, with Farrell's wife/kid, Vaughn's wife (I thought Vaughn's worst stuff was when they interacted. The dialogue there was weak), Kitsch's mom/gf/being gay, and McAdams family/relationships all in addition to a main case that spread across city & state goverments, prostitution, various gangs, crooked cops, a military contractor, the LA Riots, and hippies.
If season 1 was an A+, I give season 2 a B-. There were things there that were good, but it just didn't ever have the thing that put it over the top into great. I could point to several things in season 1 that made it great, there just wasn't ever a thing in season 2 that really made it great.