Whatever the season, it appears that Nakama Yukie as Yankumi is total and utter coolness :D.
I just watched the first episode of Gokusen 2 and Yankumi is the soul of the series! Though I did love the guest appearance by Kuma as a nod to the first series.
Despite my preconceptions, I actually liked both Kame and Jin in their roles. And it looks like this series has several other familiar faces as well, including Koike Teppei, Mizushima Hiro and Hayami Mokomichi (the last two familiar from Zettai Kareshi).
Yankumi is accidentally recruited to a school with another class full of disaster students who everybody thinks is hopeless, and decides to show them that she is the one person they can trust, and as a result they can learn things. Just like happened in the first series :).
I was a bit apprehensive before starting this series, since Gokusen 1 was so perfect. But it looks like I'll enjoy this one might be just as good, mostly thanks to Nakama Yukie :). Though I will miss MatsuJun's Sawada Shin...