Jin's childhood friend was introduced this episode, but she's got nothing on Nagi. Nagi just continues to crack me up by pointing out random puns, and acting like a doofus.
This show is certainly quite the funny/interesting one. Ribald humor all over the place but serious at times... she cracks me up, Nagi.
As for dancing OP, I prefer Rosario + Vampire CapuII, but that's because it has fanservice/prismatic colors/kickass song by Mizuki Nana. Kannagi's OP is definitely on par with that if not better, and if you watch closely, the OP was pretty comedic as well and I chuckled at it.