I really love the monster angle in Season 6 and how these monsters are out recruiting and turning people. That is the kind of stuff I love (obvious from most of my fic) and I'm glad they're exploring it this year. Makes the XF person in me happy :)
In general, I've been happy. I feel like the writing is pretty tight, the acting is great, and the characters have grown and changed (and stayed the same in many ways) without becoming OOC. There have been a couple of eps where I think TPTB could have done better with the characters, but overall I've been very satisfied.
I think my big complaint this season for the first half was that I felt they did the soulless Sam thing for too long. I know why they did it, but I still think it was too long. Glad his soul is back.
But I am a little disappointed. And this is just MY opinion. Sam will obviously be having flashbacks and some massive issues from coming back from Hell. If they swept that all under the rug, I'd get annoyed. I'm more disappointed in that this was exactly what I wanted to see with Dean in S4. I expected flashbacks. I expected fallout. I expected him to totally zone out or have fits. They built up how bad it was in Hell, and how Dean wouldn't be the same. All we got was emo!Dean who whined and had some angst.
I'm glad they are doing it for Sam since it makes sense. They SHOULD do it for Sam. I'm just annoyed they didn't do it for Dean as well. Maybe one day I will get my wish that something really cool will happen to Dean that we can actually see and Sam can angst about it.
Or maybe I'm just discouraged because my dog is sick.