Is it worth watching Darker than Black season 2?

Well it does have to do with Hei, Yin, and the girl (the story revolves around her) though Yin isn't in the actual series much.
I guess it just depends on your point of view, some swear its better than the 1st season, I disagree, i do like the 2nd season but to be honest i was somewhat disappointed, i thought it could have been better. Not very many likable characters (including Hei to a point) and most others that were, didnt get enough development.
I do recommend watching the OVA's 1st if you have the opportunity, the series makes alittle more sense ( the OVA's are kind of a setup for the series itself)
Its good but not great (in MY opinion) but you may want to give it a few more episodes before deciding for yourself. though, if your a die hard fan of the 1st season, you'll probably end up feeling the same.

one thing: Mao is entertaining to watch XD
And July is in it as well...

before watching season 2, you need to watch Darker than Black - Kuro no Keiyakusha Gaiden(4 episodes OVA) and then Darker Than Black Gemini of the Meteor(season 2) to fully understand the story.

You should definitely watch both OVA and season 2 because the story still continues with new characters and season 2 is real ending for darker than black. Everything will end perfectly at season 2.

If you want to know what happens to Hei and Yin watch the OVA. Don't watch season 2. It's really bad and it leaves you with more questions then answers.

I understand how you feel, i felt the same way when i watched SAO S2, it shows me a girl that i dont care about, The anime also didn't show much about Kirito and Asuna, but hey ,i'm here not to talk about SAO,

but instead its darker than black, all i can say is.. in my oopinion, YES... it does, try at least watched 5 episodes, if you finish this season , i guarantee you that you will cry for some reason ))))