Despite the different approach, I have to say this 'alternate-retelling' of Negima is far much better than Xebec's version, in terms of art-work. And also, I quite like it this way. The anime is more focused on a certain story and plot (so far) than in Xebec's version where Fan service and Ecchi prevailed. (Okay, I may have over said that, but you know what I mean
As for the OP, I love it! Very cool use of the 'thousands' of desks in the animation. Also, its great to see PPD related things in there again such as the blackboard!
Also in episode 1 (for those who didn't notice it):
18:33 - The Metronome you see is from Pani Poni Dash! and is often seen at the Intros. The cat you see at the bottom of the Metronome is also from Pani Poni Dash! called Kami-sama(?) (Please correct me if the name is wrong, since I havent seem PPD in ages!)
19:21 - I saw a reference to Azumanga Daioh! On the blackboard, you can see a 'Chiyo equation'! Her pigtails + a pigtail-less Chiyo = (answer not shown). Also you can see the 'あ' in the blackboard! Which is also a reference to Azumanga Daioh