I really like it.
It's tragic and heart warming simultaneously (if your on season 1, just fucking wait until the whipping scene, before that it's kinda generic and frankly boring, but afterwards you won't be able to drop it until you see some fucking cold hard justice delivered).
Plus the more technological approach to magic is a nice change of pace, even if it's not a unique idea.
Especially in season two, when the intelligent devices I think they call the staves, gain gun inspired power ups and the antagonists get all up in people's grill with weapon based melee magic. And Nanoha gets more controlled magic than just a big ass straight trajectory laser.
The season is overall much better too, S1 is more like an introduction to stuff so S2 can just run with the ideas and themes. S2 also has the most adorable little dying girl in a wheelchair as the "antagonist leader" which is captivating but oh so heartbreaking.
If she doesn't get a good end I don't know what I'll do. But they wouldn't let someone in a mahou shoujo show die, would they?