Negima!? is not to be confused with Mahou Sensei Negima!. They're part of the same universe, but are completely different stories. Negima!? is produced by SHAFT, and their crazy experimental presence is definitely noted in this show.
Story: Negima!? takes a completely different direction from its counterpart, deviating from the manga storyline. The first episode opens up with the final battle between the Thousand Master and Evangeline McDowell. Evangeline gets turned into a loli form and we then start the story with Negi Springfield. Negi starts his teaching career over at an all-girls school. The crazy mischief starts when it's revealed to his students that Negi is really a magician.
Note that this show is for comedic purposes, and should not be taken in serious comparison to the manga storyline. The plot paces itself fairly well and we get a lot of insight on the lesser known characters in each episode.
Art: SHAFT's strange art style is presented in the form of Negima!? The character designs are crisp, the art is fluid, and we get some colorful environments all around. Some of the characters look a tad bit different than their counterparts in Mahou Sensei Negima! but it still works in perfection.
Not to mention they make some excellent work of Asuna's hair.
Sound: The soundtrack of Negima!? is nothing too special. It has some nice quirky music during the episodes and transitions nicely when it gets to the 'dramatic' parts. What stands out the most is the OP of Negima!? The song is sung by the various voice actresses of all the students and has several different variations. Not to mention a full length song of the OP was in episode 19.
Character: Unlike the Mahou Sensei Negima! anime, Negima!? gives plenty of screen time to all the girls in the class. For such a large cast of characters, we get to see everyone participate in the anime. We also get introduced to some new characters in Shichimi and Motsu and a few others. From Shichimi's strange body contortions to Motsu's epic "...in a good way" line, this dynamic duo is probably the highlight of the characters.
Enjoyment/Overall: Some people hate this series because it's not part of the Mahou Sensei Negima! line or it's crap because SHAFT ruined everything, but I thoroughly enjoyed this series because it has its funny moments and because it's a different approach to an already on-going series.
Unfortunately, subs are nearly non-existant as Mahora Academy simply reduced subbing to one episode per 7 months after episode 20. Whatever the case, we're down to waiting for these slowpokes or for Funimation to release their DVDs. Hopefully they won't trash Negima!?'s dub... in a good way.