Not exactly great in the artistic sense, though it is a great example of all the tropes of otaku* media combined in 150 minutes, Nanoha The Movie 2nd:
It's significantly better than the 1st movie though. The plot is also quite complex for a 150 minute movie, given it's the plot of a manga compressed into this runtime. There is a ton of very heavy (forced even) drama. However, the amount of colorful magic rays coming out from the English and German speaking magic/electronic staffs of the flying main characters, which are powered by magic ammunition, was simply too much for me to handle at certain points. And I am a fan of this kind of thing, but here it was simply overkill: The poster actually shows a lower amount of color than you usually see on the screen at each frame of the movie. This is likely the most colorful movie I ever watched.
Theoretically this is supposed to be adult but there isn't anything here that's mature: there is not much graphic violence and no shots of nude adults. Oh yeah, I think that pedophiles are actually included as a target audience of this since there are actually shots of nude children (like this
http://en.wikipedia.org/wiki/Virgin_Killer). Thinking about it, comics and animation are actually good ways to handle this social group since in the west they usually watch photos and films of real children.
Still, it's significantly better than the 1st movie, so I give it
80/100. Yes, it's actually a quite powerful muscular drama movie (whose drama is more explicit than in Miyazaki and Ozu, more similar to Kurosawa's cinema) whose power is suppressed by simply too many colorful magic rays.
Interestingly, it's not listed on the critiker database even though it's the 13th top selling blu-ray disk in Japan of 2013 (sold even more than The Hobbit and Wreck it Ralph there).
*Otaku is a word used by the Japanese to designate teenagers and adult males who don't have much of a social life and dedicate their entire free time to science fiction, fantasy, comics books, anime and videogames. Basically, it's nerd in Japanese.