I watched the whole second season this weekend. For the most part, I loved it.
People complained about Karen and Foggy in season 1, and while they didn't bug me there, Karen bugged me more this season. She's like Lois Lane in some of thd old cartoons and comics -- always doing something stupid that should probably kill her. I also got pretty sick of Foggy being mad at Matt for doing Daredevil things; I thought we resolved that in season 1.
I've never understood the love for the Punisher, but I thought his character was portrayed well here by Bernthal. The depiction overall was really good, as he managed to be sympathetic while still coming off as out of his mind.
The season was pretty clearly divided between Punisher and the Hand. I know people were really looking forward to the Punisher, but I wanted to see more ninja stuff. Some of that felt rushed to the point I'm not sure if they explained some of the stuff that happened in the last couple episodes. I wonder if the Hand will end up being what eventually brings the Defenders together.