I haven't watched any of the Negima anime or the live action, but from what I've heard of them, I feel sorry for Ken Akamatsu.
LH anime: Shitty art, sense of humor doesn't transfer mediums well
First Negima anime: Bad art, Setsuna gets a less major role and loses most of her awesomeness, Kotaro gets left out, shitty ending
Second Negima anime: I love Negima and Pani Poni Dash, and the two mixed together don't sound bad, but its apparently pretty unfaithful
Negima Live Action: Negima's cute/hot cast gets portrayed by a bunch of fugly actresses