Well, Kuuki, I highly suggest you check out some other SHAFT anime. I consider (at the very least) Bakemonogatari as well as all of the seasons of Sayonara Zetsubou-Sensei to be compulsory for any anime fan.

And yes, Arakawa actually is becoming a bit "cliche SHAFT", but I don't necessarily consider it to be a bad thing. I'm still highly enjoying the anime. ^^
As for the manga, I read the first two volumes yesterday and loved it. The character designs aren't quite as pretty as in the anime, but otherwise I definitely prefer the manga (which is usually the case for me). I agree with everyone else that the stronger focus on Nino in the manga is really nice. And I feel like the comedy shines through a little more in the manga as well. Even though SHAFT always creates a stylish anime, all the little bells and whistles aren't really necessary when the source material is so good. The characters are lovable and quirky enough on their own.
I kinda dig the length of the chapters, too. The shortness of the chapters seemed to make this a really super-quick read for me. Well, that and the fact that the manga is just plain fun to read.